See below market that seeks to find the last surviving coach from a losing Challenge record (or that isn't fired):

Still alive going into the playoffs:

This resolves as "YES" if they previous market resolves, and the last surviving coach is determined before the first 2023-2024 NFL playoff game. If the regular season ends with more than one coach alive, this will resolve as "NO".

Also, if you want to derivatively bet between two sets of coaches (that I friend and I drafted), check this out: