After unbundling urllib3, there are no mentions of ndg-httpsclient, pyopenssl, cryptography. Also idna is bundled, so it's probably is not needed as a dep as well.
ndg-httpclient has been removed from recent requests ebuild. As for pyopenssl and cryptography, they are runtime, optional dependency. If you grep the code, you'll see reference to them. This is why we have them as optional deps. idna is listed as a dependency in setup.py.