Someone could build a combined Wayland/X server in the same process like that, but why? The only reason you would need to do that would be to run Wayland clients natively on your X server. IMO if you want to use Wayland it is much easier and more valuable to just port those tools. The hotkey daemons, screenshot tools, and command-line clients are pretty small and not that hard for someone to rewrite as a weekend project, people have done a lot of that already. The harder part is the window managers, but if you're a hard-core window manager author used to doing things the X way then you won't see much reason to switch anyway.