Good for Saban. He could have very well hung around too long. Game is changing I don't think he's interested. Kudos to him for not dragging things out and realizing that it's probably best to hand it over to the next regime while things are still in good order.
As far as the list...pretty much chalk...
Dan Lanning - top of every list college and pro most likely. Saban and Bama DNA can recruit with the best of them. Makes the most sense. Oregon is a legit top tier gig though, and Phil Knight can match any amount of money. Does he want to follow the GOAT and worry about a hot seat if he doesn't win a title in year 2?
Lane Kiffin - Can do it from a coaching, X O, recruiting, etc... everything football and on field related. Is he the right fit for everything off field though? He can very easily rub people the wrong way.
Sark - Kind like the guys above, has the resume, cred, acumen. Does he want to deal with the pressure when he can make just as much if not more money at Texas?
They could raid the Michigan staff...that DC and OC will be sought after. Offer those guys the bank once Harbaugh bounces.
Urban Meyer - You have to at least consider it. He's a multiple title winning coach. He's kind of like the Pitino of CFB. Some baggage, got an ego, might bring some scrutiny...but damn he can recruit, coach, and win seemingly with any team in any conference.
There's a lot of moving and shaking in the NFL, they could look that way. A number of good HCs and even up and coming coordinators who could do it. However, generally speaking, the NFL guys prefer to stay in the NFL. Don't like all the extra that comes with CFB.