When rustc explodes
I don't see how rust will manage to fix async await, unless making a v2 of the language. While working with sync rust is often a very pleasant experience, everytime I used async await was awful. 
To the point that I avoid using rust for web /networking stuff, any other option is better. 
It's also very discouraging to read some people telling there's no issue with async await. Of course if you use a thousands of libraries (that are more or less hacks), and never use trait and generics, it's probably a decent experience half of the time I'd say.It's something I've only encountered with rust community, in Java when a feature sucks, we just say it sucks. Even the architect that approved it will say it sucks.