I think most distributions don't intend to change /usr/bin/python to 3 in the observeble future as that will break scripts. The meaningful way in which distros work on 2->3 transition is uprading apps installed by default to use 3 so python2 can be thrown out of the default CD image.

Sources: http://radiofreepython.com/episodes/10/ (IIRC this is where I learn this but I'm lazy to listen again to confirm. I recall Barry mentioned some distro that did change /usr/bin/python to 3 and that a lot of stuff broke.) https://wiki.ubuntu.com/Python/3 https://mail.python.org/pipermail/python-dev/2013-July/12752...