One piece of software (a kind of custom package/build manager) I'm using at work still runs on Python 2. If it still works, why change it?
It's yet to be seen how this runtime will be maintained in the future. Of course, given the enormous usage of python2 it's clear that it will be possible to use it far into the future. But it's really an unprecedented situation where an enormous software platform is abandoned by its developers. If this were a commercial product, it would filter through the long tail of software graveyards like Oracle and Computer Associates. I imagine the main annoyances in the future python2 landscape will be vendor fragmentation and diverging implementations.
I've never understood where this mentality comes from. I have programs 30+ years old, and still use them because they work perfectly fine.
That’s “where this mentality comes from”.