> I can already write decent C# applications that run in browser .. it will run fine.
It is undoubtedly technically possible, but not really practicable, unless you accept an exorbitant speed-down and much higher memory consumption than e.g. when running in DotNet. Personally, I don't find that attractive in any way, nor do I find it particularly efficient.
Try with a representative application where a whole JS based single page app is implemented in another language than JS (e.g. C++/Qt), which is one of the core benefit propositions made by WASM.
It is undoubtedly technically possible, but not really practicable, unless you accept an exorbitant speed-down and much higher memory consumption than e.g. when running in DotNet. Personally, I don't find that attractive in any way, nor do I find it particularly efficient.