Lot's of huge working code bases (in-house apps) are using Python 2. It works, it's been tested, it's in production daily. What's the compelling business reason to change? And 2 to 3 is a substantial change. If we're going to do this and pay the cost to do so, we may as well investigate other options (outside of Python) while we're at it.
I'm not sure there's a compelling reason to upgrade old, working code to Python 3. The cost of having Python2 and Python3 installed on the same machine is minuscule. The hardest part is making sure scripts use "#!/usr/bin/env python2" or "#!/usr/bin/env python3" appropriately. Even on Windows, the "Python launcher for Windows" [1] will launch the correct version of Python.
My rule of thumb is write new stuff in Python 3, keep old stuff on Python 2 unless I have to rewrite it for some reason anyway.
Upgrading just to upgrade seems like developer problem more than a technical problem.
Yes you should investigate other options outside of Python, on a regular basis I keep up to date on other frameworks/languages and on a regular basis I decide that Python is still the right choice for me. If you aren't doing this on a regular basis (at least once a year seriously considering where your framework/language of choice is on the market) then I think there is a serious problem. The CS world changes so fast that you always need to consider if what you are doing is simply outdated and you should pay the cost to stay current. However if that cost still isn't worth it and everything is working on your outdated, legacy hardware and software and you can still keep up with the market than you're good.
I simply like to keep myself up with the market/community, when I release new software I try and make sure I'm not releasing something on a platform that will be dead in a month.
