I agree in general, but...
Demeco Ryans is from Birmingham (Jess Lanier H.S. in Bessemer) and was a star player @ Alabama (2002-5), so I am sure he would at least listen if called.
As for Vrabel, he would be interesting. Can he bring Derrick Henry back with him?
That being said, going from the NFL to 'Bama is not unprecedented:
Ray Perkins left the NY Giants to replace Bryant in 1983.
Gene Stallings had been the Cardinals HC (until he was fired) before he went to 'Bama to replace Curry in 1990.
Saban left the Dolphins to replace Mike Shula in 2007.
Different world now, I know, but it has happened three tiems @ Alabama in the Post-Bryant Era.
FWIW, Saban is going to be involved in the process, and I think whoever is chosen will defintiely have some kind of NFL flavor with which Saban is familiar and likes. Just thought of another: Jedd Fisch from Arizona who has deep NFL coaching (as an assistant) roots AND CFB HC experience (Arizona). My new leader in the club house!
Seriously, I have no idea. They'll probably choose somebody really obscure.