As Johnny Gaudreau sadly passed, the Blue Jackets find themselves below the salary cap, as they're sitting at $62 million, and they need to be at $65 million. If they fail to that cap floor, the NHL could penalize them.
If the NHL decides not to grant them an exemption, the Blue Jackets would need to find a trade partner looking to get rid of a contract worth at least $2.7 million, most likely costing them a draft pick or a prospect to make the trade happen.
However, these situations are rare in the NHL, and it's not likely the league will offer any leniency for the Blue Jackets, but it's ultimately all Gary Bettman's decision.