Another administrator has left NWU for greener pastures and a higher title.
It's been something like 10 years since my college has had a dean for more than 3 years, and about half of that time, we've had interim deans.
If they're good, they move up and away, and fast; dean is just a minor checkmark on the way. Associate and assistant headmaster is a step up to headmaster, and there... well, there must be a lot of turn over at higher ranks because people seem to move a lot once they move into administration.
Or not. If they're questionably competent, they can get stuck.
And sometimes, we've had GREAT mid-level administrators who stuck around a while; the folks I'm thinking of were hired from within and really found a way to put their smarts to use in creative ways here, and didn't move, for whatever reason. (Though one recently retired, and what a loss that is to us!)
One of my grad school friends is now a headmaster, and a surprising number have served as chairs of various sorts of institutions. (I'm late to the chairing game.)
I have a feeling my current chair could be a really successful dean if they want to go that direction.