Although Wayland has been GNOME’s default session since 2016, X11 has continued to linger in the codebase—until now. That changed with the recent merging of two PRs (here and here), which completely removed the X11 codebase from both Mutter, GNOME’s default window manager and compositor, as well as the GNOME Shell itself.
In other words, the GNOME project is finally closing one of the longest chapters in Linux desktop history. With the upcoming GNOME 50 release, scheduled for mid-march 2026, the desktop environment will officially drop support for the native X11 session, making Wayland the sole display system moving forward.
For me the X11 era continues for now (until the next version of xfce I expect) and the era of GNOME ended 23 years ago.