Xwayland doesn't need a hardware specific DDX driver, because firstly, many of the features can be implemented by forwarding to the Wayland server, and secondly, the drawing operations (which don't exist in Wayland) have been implemented hardware independently, based on OpenGL, in the GLAMOR backend.
If hardware vendors don't have to care about it, then Xwayland should not create a huge maintenance burden and thus I'm pretty confident it will be available until 2030; enterprise distros likely won't be able to remove it earlier anyway.
X doesn't need a hardware specific DDX driver either when running on hardware supported by Wayland+Xwayland. The GLAMOR backend works just as well for a standalone X server, and it can just use the same libraries and APIs as Wayland does for the rest of the stuff. (There's not really any kind of hardware abstraction layer in Wayland itself.) The main reason why people use the hardware specific X drivers still is because they're more mature and robust than the Wayland stuff.
Maintaining Xwayland basically means maintaining all of Xorg except the hardware-specific drivers. And Red Hat doesn't want to maintain that code base anymore. Therefore, Xwayland will soon be abandoned, then deprecated, then removed entirely.
https://blog.mecheye.net/2014/04/xwayland/
https://wayland.freedesktop.org/docs/html/ch05.html
If hardware vendors don't have to care about it, then Xwayland should not create a huge maintenance burden and thus I'm pretty confident it will be available until 2030; enterprise distros likely won't be able to remove it earlier anyway.