To me, I don't really mind reschedule mode so much. But I *really *don't like that we have *both* styles implemented in operators (talking about providers here).
I think that if we have implemented async for an operator, we should remove the non-async version. And we should remove the `deferrable` param for 3.0 -- this is something that to me makes no sense, since it implies that sensors should have both ways implemented. But users should still be allowed to write rescheduling sensors.
