Lefty Driesell used to argue for tenure for coaches. That'll never happen. The most recent example: Harvard, where Frank Sullivan was fired after sixteen years. As an Ivy, Harvard long ago de-emphasized athletics and of course does not offer athletic scholarships. Even here, though, coaches are expected to win, win, win.
On the other extreme, Tubby Smith is on the firing line at Kentucky. Great question: who would be the next coach here? It's a great job in the sense of being prominent and celebrated; it's an awful job with the pressures that come with it.