wish i had more time for the multitude of your generic "why not?"s, but i don't :(

any language (high or low level) that allows you to write and execute deterministic assembly or machine code can be used to implement whatever you want. whether WASM ever reaches this type of broad security-sensitive wild-west remains to be seen, but my money is on "never".

wasm will certainly expand into additional areas, but they will all be security-gated and will not have unfettered, raw access to all hardware (even with some additional user-grokkable permission model), because it has to run on the web: "W"asm