This is one of many ambiguities where your theology will guide the proper translation.
Chronos can mean both time itself and a period of time, or a time delay, depending on context.
an indefinite period of time during which some activity or event takes
place, time, period of time
Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 1092). Chicago: University of Chicago Press.
Both readings are valid, with modern readings influenced by post-Enlightenment thinking as well as notions of classical physics (in which time is separate and independent of other physical quantities) and thus they tend to not want to think of "end of time itself" as the proper reading of Rev 10, given that it occurs in the middle of Revelation and they prefer to treat time linearly in texts and as something unaffected by happenings in the world. As Nigel pointed out, this is not resolved by the absence of a definite article. One can speak of a located delay or an unlocated delay, just as one can speak of a located time or an unlocated time. E.g. if one was speaking of time itself earlier, then one might want to locate it later. Same for a delay. So it is on purely philosophical grounds, rather than grammatical grounds, that moderns reject the traditional translation. Here is the NICOT explanation:
Most early writers interpret this statement as a metaphysical
assertion about the end of time as a sequence of events. The
translation in the AV (“There shall be time no longer”) reflects this
interpretation.28 This is not the meaning of “time” (Gk. chronos)
here. It would hardly be necessary for an angel to put himself under
oath just to make an assertion about the timeless nature of eternity.
NICOT also includes the following footnote:
Cullmann (Christ and Time, 49) takes χρόνος in Rev 10:6 not as a
reference to an era of timelessness, but in the sense of delay. The
contrast between time and eternity is a philosophical notion and has
no support in biblical theology.
Mounce, R. H. (1997). The Book of Revelation (p. 205). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.
There are many such examples that account for differences between the KJV and modern translations that have nothing to do with textual differences or improved knowledge of Greek grammar. For example, whether Gal 2.20 refers to "faith of Christ" or "faith in Christ", again a philosophical difference not resolved by the grammar. And these differences tend to fall quite uniformly on one side or the other, which is a good reason to keep reading the KJV/Wycliffe and other pre-modern translations in order to get a pre-enlightenment, historical, traditional perspective on scripture even though in some (rare) cases there are textual, not interpretative issues at play.
Thus if you are looking for a grammatical solution you are going to be dissapointed as this is a problem of interpretation, regardless of how much the questionner wants a grammatical solution.
Many (if not most) early believers did believe that the second coming will occur at the "end of time" and did not read this phrase as referring to a time delay, as can be seen from the commentaries on Revelation that I will cite later in this answer. Thus the argument of the NICOT footnote about "time itself" having no place in biblical theology is at odds with the view of early Christians such as Justin Martyr, Eusebius, and Augustine, as well as with medieval Rabbis. This is a recurring problem for 20th Century commentaries as well as 20th C translations -- that is, modern theological academia -- as they are contradicting how the earliest Christians read these texts in the name of fidelity to those same Christians - in Revelation, in Galations, and many other places where ambiguous grammatical constructions are intepreted with a uniformly different meaning than what is given given in pre-modern Bible translations such as the Wycliffe or KJV. These differences for the most part have nothing to do with the greek source texts but are the result of reading the texts with a modernist eye.
Moreover today, there are certainly present-day believers that also hold to this view, taking "end times" to mean "the end of time", and the "last days" as literally the last days, and "end of time" in Jude 18 as literally the end of time. Indeed, if we believe that the heavens and earth will pass away and there will be a new heaven and new earth (e.g. a new universe), then it makes sense that space-time will be done away with and replaced with something else (a new spacetime? something completely different?), as modern man understands time itself be a physical characteristic of creation, just like space, and thus it too will be done away with if the old creation passes away, just as time was created as part of the old creation in Genesis (a view promulgated first by Augustine and then by medieval jewish rabbis such as Nachmanides). But the same modern man, when given the job of translators, insists that early Christians were primitive people who could not possible be thinking in terms of the difference between time and eternity, or that time would come to an end, nor do they accept any kind of sensus plenior with respect to scripture, and for these types of reasons they consistently choose the opposite interpretations of ambiguous constructions than what is chosen by pre-modern translations.
Indeed if you do not believe that the second coming is at the end of time, you will need to explain the language of "last day", "last days", "end time" used in many places as referring to just time delays, which begins to stretch credulity. Then you will also need to think of how the heavens and earth can pass away with time continuing on unaffected.
Early Christian commentaries on Rev 10.6
These are included to argue against the NICOT claim that the nature of time itself versus eternity has no place in Biblical Theology as the justification for only interpreting this as a delay and not a metaphysical change in time:
- Andrew of Caesarea (6th C):
God swears by himself, since there is none greater than he. But the
angels, being creatures, swear by the Creator, for due to our
untrustworthiness, they are the guarantors of what is said by them.
They swear either that in the coming age there will no longer be time
which is measured by the sun, since eternal life is transcendent to
temporal measure, or they swear that there is not much time after the
six voices of the angel before the prophecies are fulfilled.
COMMENTARY ON THE APOCALYPSE 10:5–6.
Weinrich, W. C. (Ed.). (2005). Revelation (pp. 149–150). Downers Grove, IL: InterVarsity Press.
Towards the close of the first vision (chap. 10:6.) it is sworn that
“there shall be time no longer:” in other words, nothing now remains
of the predictions of Holy Writ, which shall require time for its
fulfilment: and this is only an echo of Daniel (chap. 12:7.) where an
oath to the same effect is sworn, declaring that, when the power of
the holy people shall be scattered (abroad) “all these things shall be
finished.” So also here (Rev. ib. ver. 7.), when the seventh Angel
shall begin to sound (his trumpet) “the mystery of God shall be
Eusebius of Caesarea. (1843). Eusebius Bishop of Cæsarea on the Theophanīa or Divine Manifestation of Our Lord and Savior Jesus Christ. (S. Lee, Trans.) (p. cxlviii). Cambridge; London: Cambridge University Press; Duncan and Malcolm.
In like manner (Rev. 10:6, 7) an oath is sworn, “that there shall be
time no longer,” but that now, the mystery of God is finished, as He
hath declared to his servants the prophets: when, again (Rev. 11:15)
“The kingdoms of this world are become the kingdoms of our Lord, and
of his Christ; who shall reign for ever and ever.”
Eusebius of Caesarea. (1843). Eusebius Bishop of Cæsarea on the Theophanīa or Divine Manifestation of Our Lord and Savior Jesus Christ. (S. Lee, Trans.) (p. cxl). Cambridge; London: Cambridge University Press; Duncan and Malcolm.
Early Christian commentaries on Revelation
These are included to refute the NICOT interpretation that "end times" refers to "delay" as opposed to a change in the nature of time itself.
- Victorinus of Petovium (3rd C):
[This passage] signifies the Holy Spirit who through two prophets
proclaims that the great wrath of plagues is imminent. This occurs so
that, although it is the end of time, someone might in some manner
still be saved. COMMENTARY ON THE APOCALYPSE 8:13.
Weinrich, W. C. (Ed.). (2005). Revelation (p. 130). Downers Grove, IL: InterVarsity Press.
Concerning this [first] resurrection he says, “I saw the Lamb standing
and with him—that is, standing with Christ—144,000.” He is speaking of
those from the Jews who at the end of time will come to faith through
the preaching of Elijah, and of these the Spirit testifies that they
are virgin not only in body but also in language. COMMENTARY ON THE
Weinrich, W. C. (Ed.). (2005). Revelation (p. 214). Downers Grove, IL: InterVarsity Press.
- Andrew of Caesarea (6th C):
These are the ones of whom David spoke: “I shall number them, and they
will be more than the sand.” Namely, these are those who long ago
struggled as martyrs for the sake of Christ and those from every tribe
and tongue who will fight valiantly at the end of time. COMMENTARY ON
THE APOCALYPSE 7:9–10.
Weinrich, W. C. (Ed.). (2005). Revelation (p. 111). Downers Grove, IL: InterVarsity Press.
For when he says that “he shall never go out of it,” he shows that at
the end of time there will be a struggle. For it will happen that
after unity there will be a final struggle in which there will be
another separation. And wherever anyone will have been freed, he shall
certainly not go out, and he shall remain in the house, not as a slave
but as a son. And therefore God allowed those who were saved from the
flood in the ark to go out, because until that time there was still
time for returning from one’s sins. However, at the end of time it
will not be allowed one any longer to come out, for whoever at that
time will go out, will have not occasion for repentance. COMMENTARY ON
THE APOCALYPSE 3:12.
Weinrich, W. C. (Ed.). (2005). Revelation (p. 47). Downers Grove, IL: InterVarsity Press.
- Apringius of Beja (6th C):
He says that he knows the work, the love, the faith, the service and
the patience of his church. “And that your latter works exceed the
first.” He indicates that at the end of time there will be a great
number of saints, when, with the coming of the man of sin, the son of
perdition, innumerable thousands of saints will be consecrated with
their own blood. TRACTATE ON THE APOCALYPSE 2:19.
Weinrich, W. C. (Ed.). (2005). Revelation (pp. 34–35). Downers Grove, IL: InterVarsity Press.
Early Christian commentaries on the end of time
These are included to refute the notion that the philosophical view of time versus eternity had no place in Biblical theology as believed by early Christians.
If we take the millennium and think of the end of that time as being
the end of the world, we could say that it was the end of time in
general, for a thousand years in God’s sight are like a single day.
Because of this, anything that was done during the millennium could be
spoken of as done at the end of time or on the last day. LETTERS
Bray, G. (Ed.). (2000). James, 1-2 Peter, 1-3 John, Jude (p. 158). Downers Grove, IL: InterVarsity Press.
- Ignatius of Antioch (1st C):
THE COMING OF THE JUDGE. Christ died and rose again, and
ascended into heaven to him who sent him, and sat down at his right
hand, and will come at the end of time with his Father’s glory to
judge the living and the dead.
Bray, G. (Ed.). (1998). Romans (Revised) (p. 56). Downers Grove, IL: InterVarsity Press.
If someone asks why God created the world if all he intends to do is
to destroy it, the answer is that the world will be renewed at the end
Bray, G. (Ed.). (2000). James, 1-2 Peter, 1-3 John, Jude (p. 158). Downers Grove, IL: InterVarsity Press.
For instance, Daniel the prophet, under the influence of the divine
Spirit, seeing his kingdom at the end of time, was inspired thus to
describe the divine vision in language fitted to human comprehension.…
It is clear that these words can refer to no one else than to our
Savior, the Word who was in the beginning with God, and who was called
the Son of man because of his final appearance in the flesh.
Stevenson, K., & Gluerup, M. (Eds.). (2008). Ezekiel, Daniel (p. 237). Downers Grove, IL: InterVarsity Press.
- Ephrem the Syrian (4th C):
“For I know that my Redeemer lives and that at last he will be
revealed upon the earth.” Here the blessed Job predicts the future
manifestation of Emmanuel in the flesh at the end of time.
Simonetti, M., & Conti, M. (Eds.). (2006). Job (p. 105). Downers Grove, IL: InterVarsity Press.
In the pine cone nature seems to express an image of itself. It
preserves its peculiar properties which it received from that divine
and celestial command, and it repeats in the succession and order of
the years its generation until the end of time is fulfilled.
Louth, A., & Conti, M. (Eds.). (2001). Genesis 1–11 (p. 22). Downers Grove, IL: InterVarsity Press.
We cannot sin to the extent that we remain in Christ. John is speaking
here about the vision and knowledge by which the righteous are able to
enjoy God in this life, until they come to that perfect vision of him
which will be revealed to them at the end of time. ON 1 JOHN.
Bray, G. (Ed.). (2000). James, 1-2 Peter, 1-3 John, Jude (p. 198). Downers Grove, IL: InterVarsity Press.
We believe and confess that, rising on the third day from the dead,
according to the Scriptures, he was seen by his holy disciples and
others, as it is written. He ascended into heaven and sits on the
right hand of the Father when he will come at the end of time to raise
up all men and to render to each according to his works. CONCERNING
Bray, G. L. (Ed.). (1999). 1–2 Corinthians (p. 151). Downers Grove, IL: InterVarsity Press.
- Pope Gregory the Great (6-7th C):
The malice remaining in the world deserves no better than to have
those who could be of profit quickly taken away. It is to spare the
elect the sight of worse evils that they are removed when the end of
time approaches.… It is not our belief, however, that all the elect
are taken out of this world, leaving only the perverse to continue on,
for sinners would never turn to sorrow and repentance if there were no
good examples to motivate them.
Elliott, M. W. (Ed.). (2007). Isaiah 40–66 (p. 198). Downers Grove, IL: InterVarsity Press.