X11 has been, and still is, a vital piece of technology at the core of professional Unix-like workstations since decades. It has a proven track record of supporting enterprise-grade applications with long-term protocol stability and platform compatibility. It has matured over decades. XLibre is an actively developed fork of the X.Org X11 server, initiated by the most active X.Org developer and supported by the open source community.
An incompatible alternative, Wayland, is being aggressively pushed by IBM = Red Hat = Gnome = Fedora = freedesktop.org. However, it is not ready to succeed X11 as it its governance model leads to never-ending discussions and prevents even the most essential functionality from existing. Think twice before abandoning Xorg. Wayland breaks everything!
It is time that the open source community reclaims what was ours to begin with. This page lists distributions supporting XLibre so that you can make an informed choice.
--> Table has moved to https://github.com/X11Libre/xserver/wiki/Are-We-XLibre-Yet%3F <--
Please comment below in case something should be added/changed.
I'm getting more input from LinuxFromScratch and some of the people are want to keep X11, such as those using minimalist window managers. I would out LFS in the Maybe pile.