Py2 to py3 is too far a jump which is made obvious from the fork-like nature of the project. Minor changes like API deprecation is of course already taking place in most projects. Just need to strike a balance.

I rewrote 100klines at least from C#1 to C#2 when generics came in 2.0. It was compatible in that the non generic code still worked, but I don't really see what difference that made. If we didn't want to upgrade the cod me then we wouldn't have updated the compiler!

Obviously if you don't want the benefits of Py3 then you don't have to pay the upgrade cost either.