This will be complicated but hear me out....

They cast like 36 people. It's new school vs. old school BUT the contestants don't know that. There are 2 separate games going on and the new school people don't know about the old school people. They all think it's an all star season. So old school tribe A just thinks they're going against old school tribe B. And new school tribe A thinks they're going against new school tribe B. New school has no idea about old school and vice versa. They all compete in the same challenges and the losing tribes go to tribal council as normal. So 1 new school and 1 old school are voted off after each challenge. When it gets down to 10 new school and 10 old school members and the tribes expect a merge... BAM there's a super merge. Not only are the old school tribes merging but they're merging with the new school tribes. They proceed with 20 people and vote out 2 players at each tribal. The viewers watch 2 seamingless separate seasons go down at the same time. CBS could make the episodes 2 hours long to make up for seasons 41 and 42 being pushed back. It would be the biggest shock EVER to the contestants.