As for Linux from Scratch - This is something that's been on my radar, but without the part I'm truly interested in (learning more about SysV) then I'm less inclined to bother. I don't buy the reason of Gnome/KDE - isn't LfS all about the basics of the distro than building a fully fledged system? If it's the foundation for the other courses, but it still feels weak that it's so guided by a future GUI requirement for systemd when it's talking about building web servers and the like in a 500Mb or less as the motivation.
Freedesktop wants to kill X11 and are working continuously on that, to the point if rejecting patches and banning developers.
Popular desktop environments are increasingly depending on Linux-only things. KDE has officially removed support for FreeBSD in Plasma login manager (because of logind dependency).
Gnome 50 plans to obsolete X11 completely.
If you want that simple, bright future of yours, you’ll have to fight/work for it.
There is a difference of opinion. Freedesktop wants to "stabilize" X11. That does mean that they do not want to evolve Xorg. However, it does not mean that you cannot keep using it or that they are going to take it away. In fact, it is still being maintained and will be for a long time.
You can interpret the rejecting of patches and banning of developers as political. However others see the rejection and banning as protecting the stablity that is the goal.
If your goal is for Xorg to evolve and not to stabalize (fair), you may prefer Xlibre as a project.
Phoenix looks pretty cool too.
KDE Plasma and GNOME are trying to kill X11. Or, at least, they do not want to maintain support for it in their projecs. And COSMIC did not bother to add support for X11 at all. That will probably be the trend on desktop Linux.