Yes. But for one of these to really take off, I think what's needed is for one of the giants to throw their weights behind it. Basically "We're betting x billions on it, so you can be sure that lots of companies will be using this tech in the decade to come".

The XAML in Avalonia is great. There is even support for XAML to IL compilation during build so you don't have any parsing overhead when running your app.