[GoranM]

Well, I don't know what you really mean by "future proof". JavaScript will probably remain the lowest common denominator, for years to come, so from that perspective, there's no safer bet.

However, for people who want to have an edge, as developers, working in their language of choice is one sure way to get it.

There are many different developments to make that happen, like languages that compile to JavaScript, or binaries that run in the browser via NaCL; I think there's a lot of potential there.

... JavaScript was not a language designed with software engineering in mind; that much should be clear. If you can choose the proper language for the task at hand, instead of simply being forced into JS, you'll be ahead.