Right. WB's argument hinges on her story credit "Based upon the book Gravity". Their position is that Cuaron has worked his script so far beyond the original story that it would be disingenuous to honor the original contract with New Line.

That is very slick and fucked up considering that projects don't get greenlit these days without both a major star attached and an IP (book, previous film, graphic novel etc).

In other words it would be Paramount wrapping production on World War Z then turning around and telling Max Brooks "Look we know you had this contract with Plan B but we feel it wouldn't be fair to us and the rest of the writers and production staff to continue to credit you and pay you a percentage etc."

Say what you will about WWZ, it would not have been greenlit without the book and at the end of the day, cost overruns and all, the movie still made a lot of money. Without Max Brooks and Brad Pitt the rights would still be sitting somewhere gathering dust. The same goes for Gravity regardless of how much work Alfonso Cuaron put into it, his IP was not the one that got the ball rolling. It's really a shitbag move on his part that he didn't insist on maintaining credit for the original IP but after a while jerk-offs like him come to feel that they've put in so much "hard work" that it wouldn't be fair for them to share credit with the person whose work is responsible for the project's existence in the first place. The studio probably doesn't care beyond whatever personal allegiance they now have with Cuaron their big thing is that the movie was a hit and they would rather not pay Geritsen a percentage of the Net.

If Paramount prevails the implications are clear. Acquiring IP's is considered a big costly pain in the ass. Since the writers strike the idea of paying writers at all has become generally abhorrent in film. For a while producers and studio's could stomach investing in IP's because they were known commodities BUT they would rather not pay a dime more than the initial sale price. A win for Paramount would mean much greater leeway for studios to enjoy the benefits of pitching and getting the ball rolling on a project with an IP and then ditching out on any agreements past a certain point based on creative changes.