The 8UC remains what it is, and it's not going to see the light if day even once more in all likelihood. It's part of Endwalker's dirty laundry, and is better off buried for the good of the narrative insofar as the devs are concerned.

As for time travel itself, I too believe they'll likely bury that hatchet post-Pandaemonium. It's a consistently convoluted plot point that they see no further need for at this time.