Gnome developers have been debating the full support for Wayland in 3.12 for a while. They at one point even considered delaying the Gnome release to keep the development in sync with Wayland. Finally, developers have decided to keep Wayland in ‘preview’ mode as there is still a lot of work to be done.
Matthias Clasen writes on a Gnome mailing list, “GNOME 3.12 / Wayland will still be preview. There are still too many unfinished tasks, and we are only a few short weeks away from hard code freeze. We don’t want to risk destabilizing the X support at this point, so we will defer the merging of the mutter-wayland branch until after 3.12. And we will of course continue working on the TODO list right after 3.12, some of the gaps can probably be fixed in stable updates.
There are quite a lot of things that work well including, basic functionality of gnome-shell as a Wayland and X11 compositor; display configuration; color management; and message tray and hot corner. But there are a lot of things that the team doesn’t expect to work by 3.12 which include, input configuration; wacom tablets; startup notification; dnd and clipboard support; and status icons.
Should Canonical drop Mir and adopt Wayland?
Things with Wayland could had been a bit different if Canonical continued to invest engineering resources in Wayland instead of secretly working on Mir keeping Gnome and Wayland developers in dark. Wayland powered mobile devices are already in the market, most notable being Sailfish powered Jolla phones.
Canonical recently made a commendable decision to drop their own Upstart and adopt systemd after Debian picked it; the open source community is hoping that company will make the same decision about Mir and adopt Wayland which is being developed by seasoned developers and has support from companies like Intel.