I agree, but I do think it is a bit funny that you view your gadget as a blocking feature and fibers as something much less important. Both are equally "gadget"-y, as none are really needed for async io. Callbacks/promises/futures and optional posix threads will get you there.
In my view, fibers solve async io much better than async/await. Fibers look and feels like a thread and do not infect codebase with async/await constructs all over the place. And both can be made equally performant. Is fibers critical, no. I think 1.0 is much more critical. A possible future fiber implementation depend on a stable 1.0 as you put it.
