Rumors are something that Marvel will have to get used to from here on out, as speculation has run rampant about how the 'Phase Two' films like Iron Man 3 and Thor: The Dark World will raise the stakes after The Avengers. Now, we may have a much better idea of how they plan to do it. Those averse to SPOILERS will want to move along.
English stuntman/actor and current Marvel employee Andrew Lawden (Star Wars Episode 1: The Phantom Menace) recently spoke quite candidly about the plot twists and proposed action scenes for both films. Lawden's information comes from scenes witnessed first-hand, and through colleagues working on the set of Thor 2. We'd recommend taking these RUMORS with a grain of salt, but that might be easier said than done.
Last warning: BIG (POTENTIAL) SPOILERS FOLLOW!!!