The languages I listed don't really suffer from JS impedance mismatch or other major practical problems. The interop of course is still a hump from a programmer

The languages I listed don't really suffer from JS impedance mismatch or other major practical problems. The interop of course is still a hump from a programmer POV, a FFI to another language is always a portal to another culture.. But even there the shared object system and GC makes it much better than interop between native code languages. WebAssembly suitability for general HLLs is possible in the far future but there don't seem to be many eager consumers. People prefer JS interop, browser API access, and builtin high performance GC and a JIT of JS that can efficiently handle dynamic constructs with advanced compiler magic. Reimplementing those in your wasm targeting compiler would be a huge effort and complexity cost, and added bloat to compiled programs, even if wasm supported it.