Well we may as well speculate. . .
Strasser might be a good one, and while I agree that assistant coaches are usually allowed out of their contract to take a step up, which this would be, I'm not sure if that applies when the move is being made mid-season.
Barrett. . . I doubt he'd leave his cushy college job for anything less than a head coaching gig.
Doug Berry. . . has a better record as an offensive coordinator than as a head coach, but there's no way he'd accept working under the guy who replaced him, and I can't see him even being offered the position by Bauer who fired him; plus you might have a locker room revolt if he came back.
Matt Dunigan. . . has experience at being an offensive coordinator (not a great record mind you, but he was wearing too many hats and was saddled with a dreadful team and a meddling owner). . . and he's buddies with Kelly.
Milt Stegall. . . okay he's got no coaching experience whatsoever but he knows the personnel and let's face it, could he possibly do worse? And one thing would be certain. . . Milt Stegall would be on time!
I can't think of anyone else who might be available. . . I'd probably end up with Dunigan. . . he's the only one you could hire who Kelly might actually work with and not see as a threat to his position, they are good buddies after all. Any of the other ones would likely cause a locker room split and have trouble working with Kelly who would probably see in him his eventual replacement.