Though Oklahoma State lost, I think there should not be a re-match between LSU-BAMA. Its gonna be a hell of boring game and two teams from same conference should not play the national championship. Next, a team which cannot win its own conference should not be allowed to play the national championship. 

Ok, here are scenarios:

LSU vs BAMA (if LSU wins all)
LSU vs Oregon (if LSU wins all)
LSU vs Arkansas (if LSU loses to Arkansas in league)
LSU vs Oregon (if LSU wins all or loses to Arkansas and Arkansas loses to Georgia)
LSU vs Oklahoma (if Ok wins with Ok state and LSU either wins all or loses to Arkansas and Arkansas loses to Georgia)

#2 and #5 is more possible, I guess.