Yeah, MS has been very inconsistent of late. They went from Chen-style decades-long support for foundational tech, to a whirlwind of different things, promoted then chucked aside like they were a Google product.
Not really, a bunch of apps from the WinRT era are very broken under Windows 10. It’s disappointing given how much from the early 90s still works, but code from 2013 is now totally broken.
Silverlight is where things have started to go downwards wrt long-term stability. But Win32, MFC, and WinForms are still very much alive and well. I mean, WinForms even got .NET Core treatment and high/dynamic DPI support.
Yes. UWP already mostly uses WinUI 2.0 I think. 3.0 will expand the minds of applications that can make use of the component library and provide a way to gradually incorporate newer controls into older technologies (WinForms, WPF etc).
My 3 applications are written in Qt/C++. Hopefully it is going to shield me from this, as it has from the previous changes.