The feature that required David Fowler from ASP.NET team to write a set of guidelines because everyone still uses it wrong, and had the team experiementing with Go and Java approach during last Summer, and they aren't adding it because it is too complex to retrofit?

Thank god. Async/await is an okay tradeoff for Rust, which lacks a managed runtime, but it is simply a bad abstraction for managed languages, where the runtime can automagically do the right thing for you without user involvement.

async/await is syntactic sugar for futures/callbacks/statemachines in .net. kotlin does this for coroutines on the jvm.

I think green threads are a much better was to solve the problem as its much easier to reason about and debug.