(Yet another reminder that Xenocara exists, is still being maintained, and runs on Linux, or at least did a year ago)
Distros still ship token ring support; they're not going to literally "get rid of" X either.
Will GTK 5 not support X? Possibly! I don't really care though. I pretty much just use 2 as it is when I have to use GTK. But GTK and QT still support DirectFB, which is almost 2 decades old at this point. X isn't going away.