I think this is about c++-in-wasm-in-C# rather than c#-in-wasm. It's an (arguably) better way of doing FFI without having to worry about compiling the C++ dependency.
Presumably you have to compile the C++ once to wasm though?
Yeah you would, though having a common compile to target would hopefully make it easier to find pre compiled wasm binaries.
Right, some libraries are already getting official and semi-official wasm targets for the Node JS ecosystem. It would be interesting to "borrow" an existing wasm binary from npm and simply rehost it on the .NET CLR or JVM.
Absolutely... I have a suspicion that Node may actually expand its' presence as a defacto runtime for wasm outside the browser.
Not to mention, cross platform (think x86, arm AND linux, mac, windows) from a single compile target.