As someone who is working with X11, I strongly disagree. It really needs replacing badly. It doesn't even work; only a few code paths even get tested on for example GLX, which is why complex X11 apps like browsers need blacklists.

> There is a reason why Intel still stuffs the i368 instruction set in their processors

If you want a CPU analogy, Wayland is more like ARMv8, which was mostly a clean break in terms of the AArch64 ISA, but which still supports 32-bit at the process level. 32-bit and 64-bit code cannot be intermixed in the same address space, but you can run 32-bit and 64-bit apps simultaneously on the same OS, analogously to the way you can run X11 and Wayland apps on the same Wayland desktop using Xwayland. This actually worked out beautifully, and I would have preferred that x86 had followed the same trajectory.