He is actually the one re-hire that I could see working.
The problem with bringing back Carroll, imo, would be the same problem that emerged when John Robinson came back. He's been out of college football for over a decade. The game has changed. Most of the kids today, don't know a lot about what he did at USC because they weren't born when it started and were still pretty young when it ended.
Outside of the brief time with the Raiders, Kiffin really hasn't left college football, he is part of the change in style that has taken place and all the kids know who he is.
Really, the only concern I would have with him is that I don't think he pays a lot of attention to defense. You don't have to have a great defense to compete for an NC...but you have to have a solid one.