Originally Posted by Dr. Evil
I think Fox has the copyright to the world "Mutants" not "Mutation" or "Mutant."
Fox has no claim to the word "Mutant" due to these guys:
Besides "Teenage Genetically Altered Ninja Turtles" does not roll of the tongue all that well. Otherwise, Fox would have stopped the movie from ever being made.
If they did have the copyright on the word, TMNT wouldn't be covered by it. Just because "Target" is copyrighted by the store doesn't mean I can't call my gym "Target Fitness."
And the film rights aren't to the word, they're to the full concept. Marvel can't give the film rights to "Spider-Man" to Sony and then turn around and make a brand new superhero called "Spider-Man." Neither can they make up new superheroes and call them "Mutants." Unless any
company can make up new superheroes and call them mutants without violating the intellectual property that Marvel has that they sold the film rights to.
((Edit: I re-read this, and this paragraph doesn't actually make much sense the way I wrote it, and I'm not sure if it even addresses what you're saying anymore, so, yeah, sorry about that.))
They'll use the brain slot from IM3, good times, no worries.