Rust's async/await support is not intended as a general replacement of coroutines. In fact, async/await is built on top of coroutines (what Rust calls "generators"), but these are not yet stable. https://github.com/rust-lang/rust/issues/43122
Ouch... thanks; I didn't realize the Rust situation was this bad :(. FWIW, I do not look at generators as being what I would want as my interface for working with coroutines, and am very much on board there with the comments from tommythorn. I guess I just have too many decades of experience working with coroutines in various systems I have used :(.