Projecting out a year or two, I'm personally starting to run short of reasons why a non-Unity desktop flavor of Ubuntu makes sense as a value proposition. I can probably build a current KDE + Debian Wheezy derivative with less work than it'll take to continue to maintain anything similar withing Ubuntu.
For some derivatives that may be the case, but it would seem for Kubuntu specifically Canonical now has vested interest in keeping the Qt stack working really well and will start to pick up work that has been done by Kubuntu-devs previously free'ing time to working other more KDE specific stuff. I don't know, seems like a golden time for Kubuntu to me.
Ted