Both split and async fit well with the "batteries included" nature of the platform. Regardless of how much use it has seen, async is definitely an API that should be bundled with the "standard" libraries. Compare with, say, Java or Python standard libs; programmers expect modern languages to expose easy-to-use concurrency operations. Most of the async definitions are thin convenience wrappers around Control.Concurrent, so as long as we are comfortable with Control.Concurrent, I see no reason to worry about async.

In my unprofessional opinion, it's high time we add async to the platform.