And I suspect people are vastly overestimating it. The latest additions to Python look like they were made by a committee. It is the committee style work that eats up all the man hours. The programming itself is rather simple.
> Python 3 has too many users at this point.
Most were dragged along by force. Many people are happy that 2.x versions like Tauthon are still maintained. To all projects I'm personally involved in (mainly scientific) python 3 offers literally ZERO advantages and only causes additional costs.
> I don't see them keeping up.
> How do you decide what gets backported? New features will introduce incompatibility.
You gave your own answer. All features that don't introduce incompatibility are going to be backported. In that regard "keeping up" is also not the top priority.
There are a number of py3 only features pushed for by the scientific community (@ is the most obvious, but there are others).
No it's not. It is a clear regression. The minuscule performance improvements stem from the enforcement of xrange() vs range(). But using xrange() on 2.x is still faster.