C & C++ aren't going away any time soon, certainly all desktop OS work is done in those two (Linux kernel is written in C, Windows is more C++ these days). Java has found a platform in Android, used to be mainly for the web but after browsers stopped supporting applets, that fell by the wayside.
Python seems to be used quite a lot in teaching & I've seen it used quite a bit for AI. Not sure it's that viable for proper applications though.