There is not effort to "get numpy working on cython" (I am not sure what it would really mean). There is an effort to refactor numpy code between the python-dep

There is not effort to "get numpy working on cython" (I am not sure what it would really mean). There is an effort to refactor numpy code between the python-dependent part and the more core, "pure C" part, which would help. Adding pypy as a target to cython is news to me, but that also seems like a significant work given the nature of both projects. What fundamentally bothers me with those approaches is that they rely on a lot of work before even proving they can work at all. Whereas a more complete C API emulation layer would help many more projects, and give a more iterative process. The latter almost always works better in my experience.