Like @smokey said, it is DE-specific.
TL;DR: You don’t have to worry about x11 not being supported. It will be available for a few more years.
There are 3 fully-featured DEs (KDE, Gnome and Cinnamon) and several others that are close to full-featured (Xfce, Budgie, Pantheon, etc.).
Of the top 3, Cinnamon is the slowest in terms of development, but this is intentional. They don’t like breaking things just because some people want the newest thing on the block. This means that they will likely be supporting x11 for years to come, or at least offer it as a fallback.
This is also true for the others that are close to fully-featured. They are all intentionally slow with their implementations of Wayland. These DEs focus on uniformity and UX, so they don’t want things looking weird and glitchy.
It’s just Fedora (Red Hat) and Ubuntu (Canonical) pushing the idea of only using Wayland and funding KDE and Gnome to focus on it as much as possible.
However, these two are static-release distros, and all their users are using different versions of their distro. Some are using KDE 5.27, some are using KDE 6, and whatever equivalent numbers Gnome users are using. This means that they will be supporting x11 for at least another 3 years.

Aside from x11 DEs, there are also x11 WMs like Openbox, i3, Bspwm, DWM (all x11) that will probably have support for a long time.
So, you don’t need to worry about that. The rollout will take a while to happen, there’ll be some years of transitioning from x11 to Wayland, and even after it’s complete, x11 will still be supported for some time.