I knew they couldn't make it all the way to The Avengers with the original actors. It was a pipe dream as long as they didn't have it in ink.
Sounds to me it was like:
Marvel: "Here's some lowball offer."
Ed: "Yeah...I see you're paying RDJr a bit more. I'm a big star, too. Can I have that?"
Marvel: "Oh. Right. Uhhh..."
Ed: "Oh, and my usual need for creative semi-control stands. Of course."
Marvel: "Of course. It's just that....well. We can't afford that, and there's no WAY you're involved in the final cut."
Ed: "Oh. I see. Okay."
Marvel: "Right, sorry. See where Terrence Howard is over there? In the corner?"
Ed: "Um, yeah?"
Marvel: "Right. Okay, could you just go over and stand there for a bit? Thanks. really."
Kevin Feige: "Hey comic nerds, looks like Ed Norton doesn't care enough about COMIC BOOKS to relinquish his normal professional standards. If Avengers lacks a little extra 'oomph!' because we hired Nic Cage to take over as Banner, it's because Ed Norton is making fun of your love of comic book continuity! Let's judge him now!"