re: What If...

I don't think the poll voters would want to see the same teams play each other a third time in one season, no matter how good the first two games were, so I would not expect the scenario described above in which two teams in different divisions split a regular season game and the SEC title game.

The most likely way you would see an all-SEC NC game would be if some fluke happened where the best team in one division did not win the division, and the best team in the other division wins the SEC title and goes to the NC game undefeated or with one loss.

For example, this year, if Alabama were to go undefeated, but Florida suffered a fluke loss to Georgia, who went 7-1 in the SEC with the win over Florida to win the division but lost to Tennessee and Georgia Tech to fall out of contention for the national title. Alabama beats Georgia in the SEC championship game, and is ranked #1 going into the NC game, while Florida is 11-1 and in contention for the #2 spot. They would not have already played, so voters might be willing to see them play each other for the NC and might vote Florida #2.

That seems the most likely scenario, but of course all depends on what the poll voters want to see. Just because they didn't want to see a Michigan-Ohio State rematch in 2006 doesn't necessarily mean they wouldn't want to see a third game between two SEC powers who split two close games, I guess.