I nosied both Windows and import experts, and I'm about to go ping relevant numpy/scipy people on https://github.com/numpy/numpy/pull/13019

Personally, I would prefer option #1, despite the pain it would cause. It is the better long-term supported option, and Anaconda has already adopted a patch that does this. However, I think it's most appropriate to be a change in CPython at a major release boundary so that we can provide proper porting information for users.

Option #2 is kind of neat, and honestly I thought this already worked when the fully-qualified .pyd was in a folder on sys.path. However, it's going to mess big time with all of our existing build tools. So I'm not thrilled about passing on that kind of pain - then again, most people don't need this, and those who do can do their own hacks to make it work (on the theory that they're already applying their own hacks anyway).

I'm totally open to other suggestions on how to make these situations workable, though I will (continue to) push back hard against ideas that simply bring back the security concerns that led us to this point :)