Van Rossum said he is not abandoning Python entirely and will stay as an ordinary core dev. He also wants to mentor people.
It's clear from van Rossum's note he's sick and tired of running the organisation. He wrote: "I don't ever want to have to fight so hard for a PEP (Python Enhancement Proposals) [PEP 572 Assignment Expressions] and find that so many people despise my decisions."
In addition, van Rossum hints he's not been well. "I'm not getting younger... (I'll spare you the list of medical issues.)" So, "I'm basically giving myself a permanent vacation from being BDFL, and you all will be on your own".
He said he is not going to appoint a successor.
"So what are you all going to do? Create a democracy? Anarchy? A dictatorship? A federation? I'm not worried about the day to day decisions in the issue tracker or on GitHub. Very rarely I get asked for an opinion, and usually it's not actually important. So this can just be dealt with as it has always been."