There isn't a separate set of servers. The same servers (https://pypi.org https://pypi.org) are used for all Python versions, and they keep old versions of pack

There isn't a separate set of servers. The same servers (https://pypi.org https://pypi.org) are used for all Python versions, and they keep old versions of packages around. If everything works as it should (which, to be fair, it might not :) ), pip running on Python 2 ought to find the latest Python 2-compatible version of packages, including the latest Python 2-compatible version if itself if you ask it to upgrade itself. It's theoretically possible that the API used could change in a way that old versions of pip can't handle, but a) the API is super simple and there isn't a strong reason to do this and b) doing that would break the ability of old versions of pip to upgrade themselves - that is, for released versions of Python with bundled pip to work - so they're very unlikely to break the existing interface, even if they add a new one. Still, since PyPI is a free service with no support contracts, and especially because packages hosted on PyPI are uploaded by the individual volunteer authors who have the ability to delete old versions of their own packages, businesses who depend on Python 2 would be well-advised to download/mirror what they need locally to ensure continuity of business.