Hypothetical - Texas over OU
My take- a one-loss Texas-OU winner will be in the National Championship IF Ohio State loses a game. If OSU goes undefeated and a one-loss team comes out of the SEC, fair or not, the SEC would get the nod, I think. So a lot of this depends on what OSU does (if USC wins that game, I think they'd lose one in the Pac-10 anyway as deep as it is, but same situation for them as well).
That said, I think whoever wins that game, OU or Texas, they will be in the big one, barring a very weird scenario. Heck, I think they'll go undefeated.