The team itself described the stabilization of async/await as being in an "MVP" state. Stuff that's been fixed since then:
* error messages (I think there may be more to do, but they're better and better all the time)
* size of tasks (Still more to do, but they've shrunk a lot since it was first implemented
* async/await on no_std (initial implementation used TLS to manage some state, that's since been fixed)
Stuff still to do:
* Async functions in traits (this has a library that lets you work around this with one allocation, having this requires GATs)
* More improvements to the stuff above
* other stuff I'm sure I'm forgetting
> There is no runtime in the core/std but that's by design, there is no short term intent from the Rust team to do that.
This is true but with an asterick; https://github.com/rust-lang/rust/pull/65875 ended up being closed with "please write an RFC," rather than "no."