I thought MS was (quietly) killing WPF and burying it next to Silverlight? Not soon enough I think. Nice idea, headache inducing implementation.
UWP and Xamarin apps can use XAML, so it's not like the underlying ideas of WPF/Silverlight are dead.
WPF is a lot more than just a markup language for object graphs. Heck, the features I consider most essential and important to WPF (data binding, templating, and the idea that controls only encapsulate behaviour) have nothing to do with XAML at all.
Both UWP and Xamarin Forms have all of that.
But aren't all those features you mentioned part of UWP also?