That means that X case will become increasingly broken. It won't work and won't be supported, newer hardware or not.
And X won't have parity for hardware features anyway. Like HDR - it will be Wayland only. And so on and so forth. So X is fried on all ends in the long term.
It's not that it's not possible to use kernel interfaces - it's just no one will bother putting an effort in developing X because it a waste of effort. It's already happening.
What you describe is a minor annoyance at most, not at all on the same level as being unable to use X because of newer hardware. Even if it isn't fixed, one can still be worked around or just ignored, but the other just makes the whole thing literally unusable.