I've heard from some Florida State fans that the hire of Jeremy Pruitt is a lose-lose situation for Florida State, because they believe he will quickly come back to Alabama if and when current Alabama defensive coordinator Kirby Smart is hired away as a head coach. While there are many reasons to question the hire, I don't see that as one of them.
Pruitt seems to be a climber, and the next step for him if everything goes well at Florida State, is head coach. I don't see the best path to that goal as going back to coaching under Saban.
It's far rarer to see an offensive coordinator under an offensive head coach, or a defensive coordinator under a defensive head coach ending up with head coaching positions at other schools.
Why? Because the head coach will usually be given a lot of credit for the work done on his side of the football. People will always think that the Alabama defense is Nick Saban's.
There are exceptions, of course, including:
Mark Richt to UGA (Bobby's OC at FSU), Dan Mullen to Mississippi State (Urban Meyer's OC at UF), Cliff Kingsbury to Texas Tech (Sumlin's OC at Texas A&M), Carl Pelini to FAU (Bo's DC at Nebraska), Greg Schiano to Rutgers (Butch Davis' DC at Miami), Mike Stoops to Arizona (Bob's DC at Oklahoma), James Franklin to Vanderbilt (Friedgen's OC at Maryland), Paul Petrino to Idaho (OC at Arkansas under brother and John L. Smith) and Larry Fedora to Southern Miss (Mike Gundy's OC at Oklahoma State).
Just some food for thought.