> There are also numerous systems in deployment that need to have 2 and 3 running simultaneously on the same machine.
There were numerous systems that needed both 1 and 2 in the Redhat ecosystem. I agree it likely won't happen again, but mostly because the Linux distros have likely learned their lesson. It's the package managers and Linux distros with included system functionality written in some version of Python which have the ultimate say, and there are much better solutions for the problem now than when Python 2 came out. That said, it's possible some distro will make /usr/bin/python be Python 3 and /usr/bin/python2 be Python 2, if they haven't already. Weirder stuff happens all the time.
There were numerous systems that needed both 1 and 2 in the Redhat ecosystem. I agree it likely won't happen again, but mostly because the Linux distros have likely learned their lesson. It's the package managers and Linux distros with included system functionality written in some version of Python which have the ultimate say, and there are much better solutions for the problem now than when Python 2 came out. That said, it's possible some distro will make /usr/bin/python be Python 3 and /usr/bin/python2 be Python 2, if they haven't already. Weirder stuff happens all the time.