For recruiting purposes, I suspect they would always want to have at least 4 more contract years in place. So after next year, I think they would either extend him to at least 2022 or agree to part ways. How well the 2018 season goes could determine what the buy-out looks like.
For example (and I'm just brainstorming at this point), if they have a mediocre 8-4 season in 2018 but decide to retain him maybe they would extend his contract to 2022 for window dressing purposes without actually increasing his buy-out such that if they fire him after 2019 they would only need to pay his contract through 2021.
Right, I agree. Next year will be determinative, and it