The way OU recruits and is playing defense right now, they would do just fine in the sec. The reason why they tend to lose in the playoff is because they 1. played with out a defense and 2. had been pitted against the sec champ- they wont be facing the best team in that conference every week. With this enhanced recruiting outside of alabama OU would be pretty consistently better than most of those other teams. Especially, considering how most of the elite recruits out there want to play in that conference, OU would be an even more appealing destination than it is now. So it would then become even easier for OU to attract 'elite' talent in positions where they have generally only gotten 'really good' talent. like on the D line.
As far as playoffs go- it's being expanded to 12. So they'll pretty much be in every year regardless of conference.
As far as competition goes- they would likely be in a pod with aggie, texas, and probably missouri. Or they'll go to 8 team divisions, but if everyone goes to 16 teams, it'll more likely mean they'll try to go to a 4 team pod model with 3 permanent opponents and 6 rotating opponents from other pods.
But they'd make a ton of money and that's the biggest driving force here.