I agree with Jukka. Sadly I can't make it to the meeting but Eric's latest proposal (generating a new object for each occurrence of `T`) makes sense to me.
As for the `extends` syntax, I had considered modifying the lexer to make '<:' a token, since that symbol seems to be used in this meaning in some of the academic literature and maybe even some languages. But otherwise, the "call" syntax would have my preference (e.g., T(bound=Base)), since it is extensible without further changes to the parser or compiler -- we just pass everything through to a `TypeVar()` call.
PS. Alas, I cannot attend today's meeting.