@guido, AFAICT if we merge type comment support to 3.8, typed_ast will continue to live because:
- it will be essentially a backport of AST 3.8+ to previous versions;
- it will be a forward port of old, incompatible ASTs to 3.8+ (3.4 without type hints and async/await, 3.5 without var annotations and async gens, 3.6 without real async/await kwds, and so on).
That said, both mypy and typed_ast are now PSF projects so it makes sense to share maintenance cost, especially if this move actually decreases required maintenance. If having type comment/noqa support really makes it much easier to create 3.8, 3.9, and later variants of the AST in typed_ast, I say make a PR @guido and I will merge it. I hope you and Ivan will be around to help on the cpython end if there are any issues on the type comment front 