I don’t know if this is the best place to chip in specific feedback on wording in the PEP, since the discussion is still fairly high-level. But in reading the PEP for the first time, just one small clarity thing.
In the Specifications section, it’s not super clear at first glance which examples have new behavior and which don’t, just based on the verbs “include”/“exclude”. Perhaps the headings could change to:
“This includes the following examples” → "These examples may emit a SyntaxWarning or SyntaxError
and
“But excludes these” → “These examples would not emit the warning or error”