Richard Feldman (who works with Evan Czaplicki at NoRedInk) mentioned it in the Elm slack channel.

http://i.imgur.com/pqk9oMl.png

It will definitely be a very different compile target. But Elm really doesn't take any inspiration from Javascript, so I don't think it will change much about the fundamentals of the language. Of course they'll need to add capabilities for concurrency, OTP, etc.