When Canonical announced Mir, their own display server, everyone asked the same question. What will happen with the other non-Unity distros? Canonical developers are trying to solve this issue right now.
Ubuntu is not just an operating system, it's actually more of an ecosystem that integrates multiple parts, including other operating systems.
Canonical has made it clear that they need a new display server and they have come up with Mir. It's still in development and it will probably be functional and ready to integrate in an OS sometime next year.
Ubuntu has spawned a lot of other distros, such as Xubuntu, Kubuntu, Lubuntu, and so on. They are now using the X display server and some of them have even expressed their desire to switch to Wayland.
This begs the question. What will happen if the technologies can't be brought together in such a way that would ensure their continuous existence?
This problems is being solved right now (or at least they are trying) in the Ubuntu development mailing list.
“The switch to Mir in Ubuntu seems pretty risky for the existence of Kubuntu, I wonder if other flavours have the same probable problem.
“It's completely unknown how much it means Kubuntu and other flavours will need to maintain X and Wayland packages, hopefully not much (it's hardly our speciality) and hopefully Debian and Ubuntu Desktop will support it enough,” Jonathan Riddell (Blue Systems) stated.
The responses are still being posted, and this problem has captured the attention of Ubuntu's development community.
The one prevalent issue that arises from all the discussions is that the Canonical and the Mir development team specifically are keeping the developers of the other distros in the dark about their intentions, and about the Mir’s capabilities.
If you have 30 minutes to spare, the discussions in the ubuntu-devel mailing list for June will really make your day.