James Cameron tells Entertainment Weekly that he was alway confident he would get to make a trilogy of Avatar movies, even when certain industry pundits (and internet scuttlebutters… although the distinction between the two seems to be rapidly blurring) were predicting mighty flopdom.
“I’ve had a storyline in mind from the start — there are even scenes in Avatar that I kept in because they lead to the sequel,” says Cameron. “It just makes sense to think of it as a two or three film arc, in terms of the business plan. The CG plants and trees and creatures and the musculo-skeletal rigging of the main characters — that all takes an enormous amount of time to create. It’d be a waste not to use it again.”
Meanwhile, Sam Worthington has his own ideas for the sequel: "Jake should have abused his avatar and be fat and unfit and demand Neyteri to get him a beer.”