How the team looks will depend in large part on if AJ leaves or not. If they win a NC, not only is AJ likely a Heisman finalist, but he and some other key players will likely use the momentum to leave early. However, if Alabama stumbles and loses before the Heisman ceremony, he's likely not a finalist and he might not be able to gain the label of big game quarterback. Remember Tim Tebow was a first round pick, not because anyone thought he looked like an NFL quarterback, but because he was viewed as a winner. If Alabama doesn't get an NC, it will hurt the draft stock of a few players and leave them wanting to return to win a NC. This will set the stage for how difficult the following season will be. It could be a rebuilding year, I know it's not easy to say that, but sooner or later Alabama is going to be lacking enough key guys to go out and dominate.
Phillip Sims would have been the obvious guy. He's struggled some in Virginia but he'd have more to work with at Alabama, and likely be better developed as well. This is the first time in a long time that the obvious next guy up jumped ship, so it does throw things off a bit. Also, I think Blake Sims' time on the RB depth chart also blurs things a bit. If there is another injury at running back, do we see more of Blake in obvious running situations?
The problem with Blake is that he lacks the size and strength of a Cam Newton, Tim Tebow, or Vince Young. If he had that kind of size, he'd have an easier time passing, and he'd be harder to bring down. However, he is bigger than Pat White. It's not as though he couldn't run the Alabama offense, but I don't think he could run the Alabama offense quite like we are used to seeing. The question is if the coaches become confident enough in his passing to let him have the reigns. I could imagine him starting full time, but only if he develops more as a passer and it's easiest to imagine a two quarterback system. Ely could come in, in obvious passing situations, and if the team got too far behind, or if they had to score quick. I don't think Alabama would throw him out there and let him become a wreck like some scrambling quarterbacks have become. Either he'd have a short leash or they would avoid certain scenarios entirely.
Ely is the obvious choice if they want to go with one quarterback. I can't say too much in regards to him, but one would think he could run the Alabama offense. He might trend more towards JPW than AJ, we can't really tell as of yet, but he wouldn't require many changes in how they did things.
There are too many ifs with Bateman, I mean he's not even enrolled. However, he's a huge talent and it's possible that he's ready to play from day one. I find this highly unlikely though. They are not going to want to burn his redshirt unless they are absolutely certain he's ready to go from day one. How the season develops could greatly impact his playing time. If someone ahead struggles a lot, or is injured we could see more of him.
A lot remains to be seen, but it's hard not to imagine Blake Sims in the picture at this point. He's the one that's seen more than just mop up duty, he seems to be the second string guy right now. There's just a lot of reasons why Alabama wouldn't make him the main guy though.