Lets say they decided they changed their minds this year, that Carb would be better suited for the team than Martin and they fired him. (More of a bush league rangers type move)
Would Carb be forced to coach as he is under contract or would the habs then need to negotiate a new deal on top of that 3m?
In my zero formal knowledge of contracts id assume when carbo got fired paperwork was done and he was exempt from working for the habs under same contract. If that is true then you'd have to re-sign him and give him a new contract that would likely overwrite the other. If no, then I assume they could ask him to work and if he refuses he's breaching contract and would be fined or lose his salary. I'm no expert though, just a guess.