... Finally, have you asked for feedback from some more typical users of typing (that are not active on typing-sig and don't work on type checkers)? In particular, maybe it would be helpful to present the PEP to developers who use type annotations for runtime purposes, and to ask if they have concerns about the runtime semantics. The feedback could then be summarized in the PEP. I'm not sure if this is commonly done in PEPs, but it could be helpful here since a lot of developers still don't use type annotations regularly (or at all).