zlacker

I'm not them, but I don't think there's any general-purpose programming language in existence that prevents developers from implementing async runtimes and using them in their libraries.

So yes, if your whole reasoning is "other people might use async and then I won't be able to use their code", then you'll be waiting indefinitely for the magical programming language that's both fully featured for your work and does not have any portion of the ecosystem implemented in async code.