This seems only useful insofar as it shows the py3 progress, over the last few years, of the top 200 libraries on pypi.
It makes me wonder – if it took this long for the most popular libraries (those likely to have the most contributors/users/etc), how long will it take for the others (top500, top1k)?
Some will never migrate, probably indicating the project is no longer maintained. That said, I bet there will be Python2.7 running for many years after the EOL. I also wouldn’t be surprised if someone stepped up to apply security patches after 2020.