The move to the SEC will not wait until 2025. There is heavy speculation they will go after this season. Lawyers will negotiate the amount down but even with a full $80MM payout, it will only take 3 years of SEC payouts to make up for that amount.
Both schools don't want to play big 12 schedules with SEC patches on their jerseys and I suspect the remaining schools in the big 12 don't want them there either.
There will be some head hunting this fall. Lots of nasty hits and cheap shots.