For the last few years Marvel has been slowly killing off the X-Men in the comics. There are currently plans of Marvel merging the mutants with a different group known as Inhumans. People at Marvel have essentially confirmed that the reason that they are downplaying the X-Men is because of the film rights to the X-Men movies belonging to Fox studios. 

The X-Men was one of the driving forces that made Marvel comics as big as they are. The highest selling comic of all time is still X-Men #1 by Chris Claremont and Jim Lee. The most popular Marvel character, besides Spider-Man, was Wolverine. Chris Claremont's X-Men run from the 80s is considered one of the greatest comic runs of all time. It helped change and reshape the industry. When Marvel went bankrupt in the 90s, the X-Men were their biggest selling comics that helped pull them out of their financial trouble. The point that I'm getting at is that the X-Men have such a strong history within the industry, that it just seems petty to try to rid themselves of some of their most iconic characters over film rights. We have seen that Marvel is capable of working with Sony, let's see if we can get them to work with Fox as well.