8. It Sets An Almighty Precedent
For a long time it was simply assumed that Marvel would never be able to claw the rights back from any of the third party holders, because the big players (i.e. Sony and Fox) would simply keep rebooting the franchises in order to keep hold of the rights in the hope that one of their formulas would work. Even as The Amazing Spider-Man 2 stuttered with critics and didn't make as much money as projected the idea of a cross-over was still in the realms of fantasy because studios working together is usually a minefield of clashing ideas and egos that leads to messy products or lengthy court cases. Clearly, Marvel and Sony disagree - which probably has something to do with the deal being heavily weighted in Sony's favour financially and creatively - and if it works, it might just mean similar deals are possible. Though Marvel are selling the Inhumans as their version of the X-Men, they would presumably still jump at the chance of introducing mutants (especially Wolverine for the New Avengers), and crossing over with Fantastic Four would also be cat-nip for comic book fans (which might have even more of a chance if the new film flounders even slightly). Just think of the veritable tome of new stories they could adapt...