The news that XMir and Mir will not be in desktop Ubuntu 13.10 is hardly a surprise. Canonical set an aggressive development schedule and its one they are going to miss on the desktop. Ubuntu Touch is already running Mir as it has no legacy X apps due to it being yet to be released as a finished product and not supporting X anyway. But XMir is critical for the desktop if Canonical want to push Mir into the space they’ve assigned it as core to their graphics strategy.
Brief reminder: Canonical broke from the consensus development of a new display server technology to replace the X server called Wayland to develop their own display server called Mir. To make the transition and support current X applications, a way to run X applications on the new display technology is needed. For Mir, that’s XMir, for Wayland, there’s a rootless X server.
But the desktop schedule delay is going to have consequences. With 14.04 next April being an LTS release, if XMir is landed as a default in that release then it’s going to an interesting five years of support. If I was Canonical, I’d be looking at cancelling the 14.04 LTS status and moving it on to 14.10, using 14.04 as what 13.10 should have been – the release where all the glitches in XMir get shook out as the default desktop in the hands of real users. They can still release to their OEM partners with 14.04 after they’ve explained they’ll want to push an update in 2014Q4.
Meanwhile, the Wayland developers are working steadily away without the obvious pressure of OEMs and commercial schedules and will have a tech preview shipping with Fedora 20 if all goes to plan. There is no race to ship a new display server technology for Linux, but one player has been running while another walking and they don’t seem, at least from here, to be that far apart. For developers, there’s still no pressing need to choose a path either – keep developing with Qt or GTK+ or X raw and you’ll still be good for some years.