Am I the only one who doesn't worry about this? Fox would lose nothing if Marvel eventually stopped releasing comic-books and merchandises. More likely, the people who regularly buy comic-books and look for X-Men stuff would just cling into the upcoming X-Men movies since thats the only new thing they would ever get from X-Men. Merchandises, cartoons, videogames are nice things to have and it could help promote the films but its not the be all of all things.
A box-office analyst at Boxoffice.com said that How to Train Your Dragon's weekly cartoon series might have been a factor why the 2nd film didn't meet expectations because why would kids rush to cinema to watch the film when they could just watch Dragons at home. For a better comparison, lets use Spider-Man, it had a videogame tie-in for the film, a lot of merchandises and doesn't he have an ongoing cartoon series right now? Spider-man is also appearing in Disney Infinity and yet DOFP which is probably the one X-Men movie that has the least amount of merchandises, became the highest grossing comic book film of the year.
And if Marvel stops releasing comic-books, trade paperbacks, hardcovers for the X-Men, it would be their loss most especially they are releasing a dozen of ongoing comic-books every month of this year and if they are able to release a dozen of comic-books every month, it must mean that they are getting a good profit from the X-Men comic-books. Also I don't know anyone in real life who buys X-Men comic-books but I know a lot of people who watch the X-Men films. So the lack of comic-books/merchandizes won't affect the X-Men films. I think Fox just needs to be more aggresive with the marketing, make a deal with IMAX, keep the momentum they got from DOFP, keep the quality of the films and everything would be fine.