I agree, this is great. How does Debian do it?

One thing I liked about Ubuntu was how they handled the Python 2 -> Python 3 transition after version 2 was officially no longer supported.

`python` was then a non-existent command which would fail while python3 continued to work.

This way one would not accidentally run a Python 2 script which kind of worked with Python 3 but then failed under very specific circumstances, possibly even after running for a couple of days. Not even letting that script start in the first place directly after the distro upgrade was the correct thing to do.