I was advised to ask this question on internals forum, so doing so
Any efforts or tracking on stabilizing said associated types? Without them, you can't basically have both AsyncFn* lifetime link and ability to add constraints like Send onto returned future.
While AsyncFn* traits landed recently, there seems to be no tracking issue for async_fn_traits in general.
I checked RTNs but they don't seem to cover Fn*/AsyncFn* cases. At least, there's no mention how to do smth like T::call(..) while Fn*::call*, AsyncFn*::async_call* are inherently unstable.