Sadly, if USC wins out, it HAS to be them because their big games are at the end of the season. (CAL & ND).
If ND wins out, they have a shot, but not if OSU beats Michigan, or if USC loses to CAL/Oregon.
You're right, the Razorbacks have a shot. TN is a big statement game. There's always the SEC championship, though. I just hope Auburn doesn't go, because they really don't look like a championship team. Overall, I think the SEC looks weak this year (not to take away from what the Razorbacks have done.)