I agree with this. Given that Javascript is the undisputed king of browser languages, and the difficulties with Javascript as compilation target are becoming a

I agree with this. Given that Javascript is the undisputed king of browser languages, and the difficulties with Javascript as compilation target are becoming apparent, I expect that WebAssembly support will be something of a priority for browser makers. I also think that, as you point out, VM design in general has mostly focussed on sequential computation, and concurrency is bolted on later. In part that's because concurrency is much harder, and the underlying CPU support for concurrency is in flux.