This is just hypothetical, but the go statement could be an expression that returns a cancel function. From there, the sky is the limit. And in the other side,

This is just hypothetical, but the go statement could be an expression that returns a cancel function. From there, the sky is the limit. And in the other side, have a runtime.Done function that returns a channel that will need closed when the said cancel function is called. There are a bunch of other runtime functions that are goroutine specific already, so there is precedent