The other way to put this question is - Is there sufficient reason/motivation to try to replace Javascript with something else? What does JS lack or what are its limitations?
None of these things are a showstoppers, but rather amount to "death by paper cut" that in my mind that make the language unsatisfying to use.
Now that you mention it if I'm going to do that, why not use the python-to-javascript compiler from pyjamas? ... hmm.
Talking about future support, as CF is included in Rails 3.1, I guess that it should be guaranteed enough.
In that context, I read "etc, etc" as a variant of the "etc" operator.