If we have Divisions then I'm assuming they'll assign one x-div perma-rival.
If we use pods, I guess they can still do that but it starts to impair the scheduling flexibility that's the primary benefit to using pods in the first place.
Anyway, my preference for a x-div perma-rival from all schools currently in the East, would probably be Georgia, Florida, or Tennessee, in that order. Obviously those schools might already have their dance card full with a more traditional SEC rival, in which case it doesn't really matter to me who we'd get annually out of Kentucky, USCe, or Vandy.
As you note, having permanent inter-divisional games undercuts the reasoning for going to pods (sub-divisions).
It's easy for me to say this, as the fan of a going-to-be "newbie" member of the SEC, but I'd rather there not be permanent non-divisional (or sub-divisional) games. For one thing, they cement scheduling disparities in place. (I suppose that could be addressed by rotating "permanent" games, but then what's the point of having them?) I'm looking forward to seeing OU play the eastern powerhouses of Alabama, Georgia, and Florida as much as old conference-mates A&M and Mizzou. I would be disappointed to see the interdivisional big dogs come to Norman only once a decade or so.
IF permanent rivalries are the deal, while OU has a little history with Tennessee, I like Cincy's idea of UT vs. UT, two orange helmet programs that haven't acted like helmets lately.
As for OU, I guess I'd pick the crimson school of the east, Bama. But Bama's already got a boatload of permanent rivalries, so that might be out of the question. So, then, Georgia.
My ideal would be subdivisions where you play the 3 other teams in your own subdivision, all 4 teams of one other subdivision, and 1 each team from the other 2 subdivisions. After 8 years, rotate the subdivision vs. subdivision lineup. I suspect that most folks would find that quirky, so my fall-back would be play your own 3 subdivision mates and 2 each from each of the subdivisions. After 6 years, you would have played at least a home-and-home with every school in the conference.
I'll bet it's going to be divisions, and I'll bet there will be permanent rivalry games.