One problem with this PEP, which I didn't see mentioned in the other replies, is that it tries to grab "?" character, which is already sought-for by another pending PEP: "PEP 505 -- None-aware operators", https://www.python.org/dev/peps/pep-0505/ .
I don't think PEP 505 is much of a concern. It's from 2015, and
it's marked "Deferred". I suspect if it was going to happen it
would have happened by now.