At the language summit this year, there was some discussion of PEP 575. I wanted to simplify the PEP, but rather than modify that PEP, Nick Coghlan encouraged me to write an alternative PEP instead.
PEP 576 aims to fulfill the same goals as PEP 575, but with fewer changes and to be fully backwards compatible.
The PEP can be viewed here:
P.S. I'm happy to have discussion of this PEP take place via GitHub, rather than the mailing list, but I thought I would follow the conventional route for now.