Maybe not everyone will think as I do, but I don't consider WPF "dead"; I consider it "done". Put simply, it has all the features I want and then some, except for those that would require an entirely different design. It also has enough inertia that, although they may stop developing it further, Microsoft will be forced to keep it working for the foreseeable future, at least on Windows desktops (which I expect are the main target of most WPF developers). It's thoroughly documented, there's sample code for nearly anything you might want to do, and it doesn't even have many bugs left.
Given all of that, I don't care much if it doesn't get any further development. To be entirely honest, I have worked with frameworks that get an update every week and have loads of enthusiasts, and although they do tend to have very clever designs and lots of potential, they also tend to be buggy as all hell, poorly documented, and lacking critical features. There's also always a decent chance that new shiny framework will not catch on, and have development stopped before it gets debugged, documented, and completed. Then you'll be in a bad place indeed.
It's great that work is being done on UI frameworks. God knows the field needs it, and as I mentioned earlier, some of the shortcomings of WPF cannot be addressed with anything but an entirely different design. But I wouldn't look down on mature frameworks as "dead".
I wouldn't welcome random "improvements" on WPF made just for the sake of changing something. Sometimes you stop working because the work is done.