If they asked me, I'd say an open RPG for Battle Angel Alita. She already has amnesia, there would be tons of possible quest arcs/factions, it has the deepest story (surprisingly) I've ever read, and James Cameron could use a larger base of BAA fans before he finally gets around to making the movie. Cameron of course is focused on the action aspects of the manga, so he probably won't feel threatened by any other interpretations of the story.