In 2011, Barkley was USC's quarterback for 99 percent of the Trojans' 12 games (an estimated guess, but probably accurate).
Expect the same in 2012, barring a potential injury or total destruction of an opponent. But even the 50-0 rout of UCLA didn't remove Barkley from USC's season finale last season.
And at Barkley's press conference, Kiffin said he expects to challenge his captain in new ways, and make him "the best player in all of college football." If that goal were to materialize, it wouldn't happen from the sideline.
What the other three have to do now is wait. That could be a tough pill to swallow for Scroggins, who will be entering his redshirt sophomore year. But if he decides to transfer instead of compete his junior year with two sophomores, he'd still have to sit out a year anyway. I'm sure he and his family will have a discussion with coaches anytime now.
I wouldn't be surprised if he did leave, though. Both Kessler and Wittek can play and they will challenge Scroggins for a starting spot, when that time comes. As of now I think Scroggins would come in for Barkley before the other two, but Kessler also showed he was a capable athlete filling in for Scroggins as a QB2 while Scroggins rehabbed an injured hand.
As for Wittek, I could see him being great in two years. He appears to have everything you want in a quarterback, except for the game experience. Coaches aren't totally convinced he'd play better than Kessler right now, if given the chance, but Wittek's improvement over the course of the season was great. He looked more comfortable moving about the pocket, and threw a few beautiful balls in practices. Still, as we all know, technique only goes so far. It's what you do when the lights are on that counts, especially as a quarterback at this program.
In sum, Barkley will play nearly every offensive snap of 2012, barring any potential injury. I would expect either Scroggins or Kessler to back him up next year, as of now leaning toward the former. And then come 2013 or 2014, I could definitely see Wittek reach his full potential.