The challenge now is more on the JS VM side, optimizing the Emscripten-generated idioms and the typed array memory model. Also, longer-term, we're working on JS language evolution via Ecma TC39.
These are focus areas of the team I just mentioned.
Well we agree. My answer is not to justify PNaCL, but to let you know that when you say "we commit to this", it means we give some serious investment on Emscripten and building a community. So far Emscripten has only been mentioned as 1-2 slides on each JS talk. And I think we both agree that a serious project as it is, it needs a few people building posting updates and letting everyone about the great work that is being done by @kripken.
These are focus areas of the team I just mentioned.