You are right they wouldn't fight tooth and nail because they wouldn't have to. Infact the burden of proof would be on Marvel to prove they aren't breaching the contract not Fox to prove they were. You don't have to sue someone for breach of contract if there is no legal issue to be debated. Which again there isn't they just fax a judge a paper and Marvel is legally required to stop or pay damages and stop. Do you really think that you have found some loophole that a person making hundreds of thousands of dollars practicing law has over looked? If things worked the way you think there would be 8 million star battle movies staring like sky crawler and han multiple and the continuing adventures of the kedi Knights.