X11 is not dying because of Wayland, it's dying because it became an unmaintainable code mountain over the years since it has been tried to be converted to something which is not designed for in the first place.
...and I'm saying that as a person who likes X11.
That's Xorg. X11 is dying because Xorg is dying and Xorg is dying because all its developers quit and went to Wayland. There's Xlibre too but it's a shitshow. Any one of us here could continue Xorg maintenance but we're not.
There is a maintained fork of Xorg that is banned by several distributions.