The reason you won't see a bytecode VM replace Javascript is because bytecode is either interpreted (slow) or JIT-compiled (complicated but faster). If you go for speed and JIT-compile bytecode, why not just compile your source and dispense with bytecodes altogether (as V8 has done)? This gives other runtime implementers the freedom to choose whether to create an interpreter, compiler, or some other execution mechanism, and the programmers the freedom to code at a high-level.

Bytecode, as distinct from object code, is on the way out. Consider Javascript a portable high-level object code and move on. If you want other languages, compile them to Javascript. Semantic affinity between source language and execution environment (e.g. is "0" false, as mentioned elsewhere) is an issue you'll need to address regardless of whether you're using bytecode.

Also, don't underestimate the power 'view source' had in making Javascript perhaps one of the most widely-adopted programming languages in the world.