The basic interfaces are built into the standard library, precisely in order to ensure compatibility across the Rust ecosystem. So if you're writing something

The basic interfaces are built into the standard library, precisely in order to ensure compatibility across the Rust ecosystem. So if you're writing something that's compatible with the basic futures/async model, you'll be able to use any provided runtime with Rust. It may be possible to do even better in the future (use HKT to enable the exact same code to be compiled as either "sync" or "async"-based) but I'm not sure why you think that the previous model of making Rust into yet another heavy runtime-based language (with a handful of weird, tacked-on functional features that would not even help performance to any real extent given those prereqs, but still making the language even harder to grok than Haskell!) is preferable.