@Ceili,
What constitutes readiness? If people in general wait until they're "ready," they could potentially be waiting for the rest of their lives. It might be just better to take a leap of faith with promotion matters, then adapt and handle it as necessary, and accept what may come.
I mean, as long as politics and/or favors aren't involved, if someone is chosen to be next in line for a promotion, the upper level have seen something in that individual that makes them the best person for the position.