ES6 Transpiler for Rails?

Does anybody know of any work being done on an ES6 transpiler for Rails? This seems like a basic thing for the asset pipeline, like coffeescript to js support.

Related to this question, but different in that we’ll probably have to transpile for a while.
http://parley.rubyrogues.com/t/what-is-the-timeline-on-es6/1841

Seems like most of the JS toolchains support transpiling to es6:

I’ve created a sample WebPack project that compiles JS (and React JSX) in ES6 to a JS bundle for Rails: GitHub - justin808/react-tutorial-hot at es6. I’ll soon be writing about how to set this up.

Possibly, something like WebPack should be integrated into the asset pipeline?

I haven’t heard of any project for this.