Grammar
καὶ ὑμᾶς νεκροὺς ὄντας [ἐν] τοῖς παραπτώμασιν καὶ τῇ ἀκροβυστίᾳ τῆς
σαρκὸς ὑμῶν, συνεζωοποίησεν ὑμᾶς σὺν αὐτῷ, χαρισάμενος ἡμῖν πάντα τὰ
παραπτώματα. ἐξαλείψας τὸ καθ᾿ ἡμῶν χειρόγραφον τοῖς δόγμασιν ὃ ἦν
ὑπεναντίον ἡμῖν, καὶ αὐτὸ ἦρκεν ἐκ τοῦ μέσου προσηλώσας αὐτὸ τῷ
σταυρῷ· (Colossians 2:13-14)
And even though you were dead in your transgressions and in the
uncircumcision of your flesh, he made you alive with him,
having forgiven all your transgressions. He has canceled what was
against us, a certificate of indebtedness expressed in decrees opposed
to us. He has taken it away by nailing it to the cross.
συνεζωοποίησεν ("made alive together"), χαρισάμενος ("having forgiven"), ἐξαλείψας ("canceling/blotting out"), and προσηλώσας ("having nailed") are all in the aorist tense and thus say the least about the verbal action possible (it just happened).
ἦρκεν (he has taken up/set aside) is a perfect active indicative verb, and thus the Colossian Christians' record of debt ("certificate of indebtedness") had indeed come to be set aside (or taken away).
Does 'all' include future transgressions?
The grammar really doesn't say. You would have to look at the context of the entire passage and epistle, but even then there would be speculation. You could easily argue that all transgressions includes future ones, but you could also argue that it only includes all transgressions up to that point in time (the latter of which is fully supported by the grammar, but without precluding nor fully justifying the former argument). The English translation is actually very good here in both the ESV and above.
To answer the specific question, "exegetically, without bringing theology to the text," it is clear that Paul is saying to the Colossian Christians that
... even though you were dead in your transgressions and in the
uncircumcision of your flesh, he made you alive with him,
having forgiven all your transgressions. He has canceled what was
against us, a certificate of indebtedness expressed in decrees opposed
to us. He has taken it away by nailing it to the cross.
Anything beyond this would have to come from something other than the grammar, although the grammar would not conflict with either position in this case.