Julia is an extremely interesting language, in some ways it is more "pythonic" than Python (at least in regards to consistency), while also being surprisingly lisp-like. Unfortunately, the library ecosystem is still extremely immature. Within ten or fifteen years, I expect Julia will take over pretty much all of Python's niches.
As for systems/backend code, I'd bet on Scala over go; much more interesting language, and able to leverage the massive java ecosystem.