Originally Posted by Zarex
Working together is wonderful, if Disney/Marvel never wants the rights to the X-Men back. Because of horribly lopsided deals struck back in the 90s, Marvel takes in a miniscule amount of the profits from X-Men films - I've heard it rumored at < 5%, which given studio accounting means that they have basically given the rights away for nothing.
Because of this, it is in the best interests of Disney for the X-Men movies to fail, which is why you won't see stores filled with film merchandise for X-Men (or the FF) like you see with Spider-man or MCU films. Despite negotiating horrid deals, Marvel held onto control of the merchandise rights for all of their properties.
This move is an interesting one by FOX, but it could backfire. If this is a late addition to the script, Singer may be just setting up a character for Whedon to knock it out of the park.
Even if Marvel makes <5%, that's still more money for Marvel. And it would be far more beneficial for Marvel it it was making <5% of $700 million as opposed to $300 million.
If Marvel and Fox work out a deal, this might benefit both companies, especially if this move proves successful. This can open the door to more inter-company deals, between Fox and Marvel...and potentially between Sony as well.
I think the most important thing is to hear Marvel or Whedon make an official statement before we make too many assumptions. For all we know, Whedon and Singer could've planned this all out together from the beginning. We don't know yet.