Among the projects that Ubuntu left aside was MIR, the famous graphical server that intended to replace X.Org and be one more option with Wayland. Finally Ubuntu, like the main Gnu / Linux distributions, will choose to use the Wayland server, but it is not something that will happen in all official Ubuntu flavors.
One of the official flavors has chosen MIR, Canonical's controversial graphics server. This server will be in future versions, not opting for Wayland and assisting in the development of MIR, as indicated by the project leader.
Ubuntu MATE will be the official flavor that I choose MIR. The reason for this choice is very straightforward and simple. Wayland's development for MATE and its window managers is still very basic. Adapting everything necessary to Wayland would be a very big effort for the Ubuntu MATE team, something that is not the case with MIR, which, oddly enough, has more developed MATE support than Wayland. That is why MIR has been chosen and not Wayland.
MIR will continue to have support and development thanks to Ubuntu MATE
MIR in this case will be in charge above all of the compatibility layer between the window manager and the Linux kernel. A very important process because it will be the reason that MATE works correctly or not. Martin Wimpress has confirmed this choice as well as the idea of continuing with the development of MIR, a development that has been a bit separated by Canonical. This will not mean that in a month or in half a year we will have a stable and final version of MIR, but it does mean that development will continue and MIR may finally be the graphical server for Gnu / Linux distributions.
I was personally surprised by this news. On the one hand is the antecedent that MIR was born because the development of Wayland was very slow. This made most of the free community participate in the development of Wayland; months later Wayland has surpassed MIR as a graphic server. In addition, Canonical "recommended" using MIR in the official flavors, something that generated quite a lot of controversy within the official flavors because they preferred Wayland. And now when Canonical goes to Wayland, Ubuntu MATE chooses MIR. In summary, MIR is always surrounded by controversy, a controversy that does not help development, although this may change substantially, don't you think?