I found just the right theological journal article Eschatology in John's Gospel for your question, authored by W. Robert Cook (Western Seminary, d. 2015), published in Criswell Theological Review (1988). The article addressed:
- The apparent "discontinuity between the eschatology of the Synoptic Jesus and the eschatology of the Johannine Jesus"
- Additional verses in John that are eschatological
The main point of the journal article is to explain how the Gospel of John presents eschatology "Christologically" as well as emphasizing the "already fulfilled" dimension more than the "not yet completed" (as in Revelation). At any rate, if we believe John to write both the Gospel of John and the book of Revelation, it makes sense to separate the 2 dimensions into two books, where each book will have a different focus. Also, since the other gospels were already in circulation, why repeat the treatment that other books already cover? The Gospel of John is known to have a very different narrative strategy than the Synoptics, so once John decided on that strategy combined with the goal of presenting Eschatology described above, it makes sense that it comes off to us very differently, yet pointing to the SAME Jesus from another angle.
From the conclusion:
When allowed to speak for itself, the text of John's Gospel has a
significant eschatological message for the church. There is no question
that it is multi-dimensional in that it speaks to both the "already" and
the "not yet" of Christian revelation. It also includes reference to both
I the above and the below, the heavenly and the earthly. Further, John
points out the implications of eschatological truth for both the believing
and the unbelieving. One may reject the implications of eschatological
truth, but that person may not escape its ultimate realities.
Eschatological truth in John is basically Christological. For the
most part it issues from Jesus' teaching and, to a large degree, focuses
upon him. Whether the subject be death, heaven, judgment, eternal
life, resurrection, or Christ's return, he is directly involved.
Finally, eschatological truth in the Gospel of John is preeminently
practical. It is immediate and fundamental, bearing on everyday life.
The possession of eternal life transforms this life and the life to come
from mere existence to ultimate meaning and significance (12:25). The
haunting and destructive fear of both physical and spiritual death are
remedied in Jesus Christ (5:24; 11:25-26). Death will not have the final
say because he will raise each one who believes in him (6:39-40, 44).
Hope, which provides life with perspective and focus, is ours in the
anticipation of being with him and beholding his glory in heaven
(14:3; 17:24). God's wrath (judgment) is the assured but not necessary
anticipation of all who reject Christ (3:36). His return offers relief to
the troubled and faint of heart (14:1-3).
As John records elsewhere in response to our Lord's promise, “I
am coming soon," so we repeat with the church through the ages,
"Come, Lord, Jesus" (Rev 22:20).
