- Double forward ref: IMO this can be resolved in the get_type_hints() functions. (Łukasz do you agree?)

- inspect.signature(): Maybe this could switch to using typing.get_type_hints()? Then again if performance is important here maybe we cannot change anything.

- dataclasses hacks: these should just be resolved.

Another thought: maybe some of these issues can be considered bugs in 3.9 as well, and we should fix them there too? That might help us decide the right path forward. After all we should really encourage people to start using `from __future__ import annotations` in their code, to help them get ready for these issues in 3.10.

Final thought: I know at least the Dropbox client team, and possibly also Instagram, has already turned on `from __future__ import annotations` by default in their local fork of Python. Maybe we can ask them if they ever felt the need to change inspect.signature or typing.get_type_hints.