From what I understand Elm is planned to target Node eventually. However the language is pretty young right now and the main work is going into making client side Elm the best it can be. The language author doesn't want to branch out too far.
You'd think Beam would be a very different compile target than JS, and it seems weird to make such a huge change without very good reason.
The Elm folks have been fairly buddy-buddy with the Elixir/Phoenix folks, so this doesn't surprise me
It makes my heart sing that a different VM than JVM or .Net is gaining more traction, and as a static types fan it makes me happy that a statically typed language may be getting on Beam.
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.