... Yes.
EDIT: I'm not sure if I even follow the question. JS isn't a drop-in replacement, not even close, and Python doesn't look like JS any more than it does any other in the C family.
If you only want one language to work with and are already learning JS then, by all means, stick with it. It's a nice language.
If you think you should learn another, go for it (and not necessarily python). It's highly unlikely that one language will die or lose popularity just because of another language. Specially not a popular one such as python.