I disagree with calling C# "easy to use". But Rust is such a bad fit for wasm that any other language will probably displace it once it's viable.

The DOM has it's own lifetime decisions, but lifetimes are the most central concern for Rust. I don't think both can be conciliated without a major rewrite of one of those parts.

If someone will build a GUI cross platform toolkit it will be in Rust, not C#.

I find Rust more pleasant to use than C#. If you had said F#, I woud be like "maybe" but not C#.