> That's only true if you ignore all packages on PyPi.

Presumably any packages worth maintaining will have far more dependent projects, so it's still far less overall effort.

> It's extremely hard to keep compatibility with Python 2

So don't? I don't think most of the people dragging their feet on the upgrade need or even want new features. A stable python 2 branch with bug fixes and security patches would suffice for most and be ideal for many. Over time the bug fixes should trend to zero and there probably aren't a heap of security issues in python projects anyway.