The biggest problem I have is that Python 2 works "good enough" and upgrading to Python 3 does not have many benefits, other than lots of work and slower performance. I guess a lot of people feel the same way, hence the slow or non existing adoption of Python 3. I guess Python 3 might end up as Perl 6 if this continues since we keep investing time on Python 2.x libraries and features.
What we need is a reason to upgrade and the killer feature of Python 3 could be performance. I would upgrade to Python 3 in a instance if it offered a lot better performance than Python 2.
How do we achieve better performance? Adopt PyPy as the reference implementation for Python 3 and all future references. Making PyPy a centerpiece of Python 3+ would probably mean it would mature faster.
PyPy is focused right now on Python 2.X, but I would rather see it focus on the future of Python and being a killer feature of Python 3+.