Last week I wrote about Mir Still Causing Concerns By Ubuntu Derivatives -- a discussion that raised concerns by Kubuntu developers and other *buntu derivatives about what options are left for them when Ubuntu switches over to the Mir Display Server with the Unity 8 desktop.
Canonical engineers in early discussions seemed to think KDE and GNOME would still see their light and decide to port their desktop environments to supporting Mir, in addition to the already present X.Org support and the Wayland support that both desktops are also working on. At least one Canonical engineer also claimed to be interested in to working on the KDE/KWin Mir support if he had some guidance, but ended up being turned down as the upstream isn't interested.
Days later, this in-fighting about what to do about Mir for Kubuntu and others in the Ubuntu family is still going on. There really isn't anything too particularly interesting going on. Basically the GNOME and KDE stakeholders don't see much of a reason in supporting Mir besides cleaner Ubuntu support in the future. They really aren't turned on by supporting Mir as long as it remains a single-distribution solution and that Mir at present has an unstable API/ABI. Canonical employees meanwhile are trying to convince them that Mir is the right thing to do.
Those wanting to pour through the latest mounds of "non-Unity flavours and Mir" emails can find them in this mailing list thread. At least as of this morning, there's still no signs of this discussion letting up.