Neither Apple nor Microsoft are supporting WASM on the desktop. Being able to run basic command line programs on top of POSIX? Sure, that'll be possible. But that's also
already possible without WASM, and yet still very rarely done.
Having actually portable APIs and abstractions such that you don't need to be concerned with differences in file paths, system behaviors, system services, audio, video, windowing, input, etc...? Yeah, WASM isn't the answer to that and it's not trying to be either.
The reason Java/.NET "failed" had nothing to do with being driven by only one player and everything to do with the abstractions are so high level at that point as to be problematic. Which you either need to fully embrace, and end up with Electron, or you end up trying to reinvent WxWidgets or AWT and the clunky compromises that result where it's really just easier to build a platform-specific binary
Also both Google and Microsoft have (or currently have) their own Java bytecode runtimes. So that's not even locked up by one player, and just compare Android vs. desktop JVM to see the inevitable future of "portable WASM"
