I will provide a brief preview of Alabama for 2012. For the sake of brevity I won't support much of what I say with facts, but if you have questions or doubts about what I say, I'll be happy to respond with more detail.
Alabama will continue to be the most talented team in college football, and after wrapping up their 4th #1 ranked recruiting class in the past 5 seasons, the gap between Alabama and the rest of college football is widening, not shrinking. The amount of talent Saban has amassed on the Alabama roster is simply mindboggling. In other words, Alabama will out-talent every single team they face in 2012/13 including LSU. Does that mean they will win every single game? Not necessarily.
Offensively Alabama may field their best offensive team in school history. With basically everyone coming back from the best offensive line in college football in 2011, Alabama will easily have the best offensive line in the country again. They will also have the best RB corps in the country with LSU being the only team that could have an argument.
Moreover, McCarron, in his second season, will have a bigger, stronger, faster and more athletic group of receivers to throw to. Playing behind that offensive line should be conducive to McCarron having a monster season, and I wouldn't be shocked if his name is mentioned in some Heisman discussions. Right now it's hard to see Alabama doing much punting in 2012.
With Alabama losing the bulk of their defense from last season, the questions about the 2012 team arise on the defensive side of the ball. As I said above, the one proplem they won't have is talent. The amount of talent they have accumulated on the defensive side of the ball should be illegal. Thus, there will be no drop-off in talent from last season. If anything there may be a slight talent upgrade, and that's a scary thought indeed.
The big question for the 2012 defense unit will be leadership. If they can come close to replacing the leadership that Mark Barron and Donte Hightower provided to the 2011 defense last season, they will have the potential to be one of the top defenses in the country again.
Alabama also will welcome the top high school place kicker (Adam Griffith) in the nation to their roster in 2012. People that I've spoke to who are knowledgeable about place kicking believe he'll be Alabama's starting place kicker in the Michigan game.
Several people in this thread have correctly pointed out Alabama's biggest obstacle which is their schedule. Some national pundits have deemed it the toughest schedule in the country, although I'm not ready to buy into that before I've seen anyone play a snap.
Alabama's biggest obstacle will again be LSU who will have 2 weeks to prepare for their "Game of the Century III" rematch. Having an extra week to rest, heal and prepare will be a gigantic advantage for LSU. The only thing Alabama can take some comfort in is that the visiting team usually finds a way to squeek out a win in this rivalry.
I think 2012 will be pretty much a repeat of 2011 in that Alabama and LSU will continue their run of being the best two teams in the country. Just as I gave Alabama the edge this past season because of their homefield advantage, so will I have to give the edge to LSU next season for catching Alabama at home with an extra week to prepare.