I don't think you'll see an official scheduling agreement or 1 big contract.
However, I think the most likely thing next round is Fox sits down with the Big12, Pac12, & BigTen together and says "If we're your highest paying TV partner, we need some considerations & cross-conference cooperation. We need to get common language across contracts to give us more flexibility in creating schedules with a bigger picture approach."
I think those things could include:
-Influence in cross conference non-con games & dates
-Ability to work to change non-con match-ups & dates 1-2 years out
-Change how weekend selections are drafted, including common language that gives Fox more flexibility in-season
-Influence on conference scheduling to spread out big games across conferences across weekends
This could include things like encouraging Nebraska & OU to play more often & give Fox first shot at it. It may force the conferences to take a little less from ABC/ESPN or get creative in how games are flowed to ABC/ESPN to keep everyone happy while giving Fox the ability to effectively treat those three conferences as one big conference from a scheduling standpoint.