I think the last sentence of you really also is in part its own cause. People excited about Python 3, are not using PyPy since it seems like it is not maintained at all.
At least adding the same improvements that were added to the 2.7 interpreter would put a bit of confidence in that. Most libraries also support up until CPython3.3, which as far as I know is mostly caused by the fact that the "u" string prefix is allowed again. So just adding that and keeping the core up to date with the PyPy2.7 releases would make it usable.
This could very well inspire other devs to add support for the other features that they are missing from later releases CPython3 releases.
At least adding the same improvements that were added to the 2.7 interpreter would put a bit of confidence in that. Most libraries also support up until CPython3.3, which as far as I know is mostly caused by the fact that the "u" string prefix is allowed again. So just adding that and keeping the core up to date with the PyPy2.7 releases would make it usable.
This could very well inspire other devs to add support for the other features that they are missing from later releases CPython3 releases.