We try to use Python 3 at work but have to run Python 2 as well because there are still packages that weren't upgraded and it's too much working re-writing them all for no direct benefit.

We also have third party vendors that only support Python 3 in experimental versions, and there not even recent versions (Bloomberg is a great example).

I really like Python3 features, but the pain of using them drives me towards using other languages. I hope Julia will be stable and mature enough soon so that I can dump Python all together. I really like Julia, but currently the changes in the languages are too fast and there are constantly incompatibilities with packages that don't update fast enough. But I'm reasonably certain that this will be fixed once they reach 1.0.

I'm sure Python is far from dead, but can imagine that Julia has the potential to kill it in many domains.