This actually is much different. The parties will be arguing over the meaning of the terms of a contract. Assuming that the terms are ambiguous, the parties can introduce industry custom to prove their meaning. The Hossa, Pronger, Luongo contracts would be proof of an interpretation favorable to the Devils.
In addition, where a contract is involved, a party can not enforce its terms arbitrarily (it's called the implied covenant of good faith and fair dealing).
Maybe this goes to arbitration, but I think it's more likely that Lou/Vanderbeek go to Bettman and ask him where the line is. It gets sticky if the Devils can't live with the cap hit associated with a contract that the NHL will approve.