User blog comment:LoveWaffle/We Didn't See It Coming - Iron Man 3 and the Future of the MCU/@comment-1713281-20130513193546

Avengers 2 casting doesn't concern me. RDJ has flip-flopped on this one, and he will likely finish out Avengers 2 (after that, it's a toss up). Samuel L. Jackson can fight for money all he wants, but I'm fairly certain he doesn't have the high-ground, since he's tied into that massive contract he had when Iron Man finished. Chris Hemsworth will likely be paid to stay on, since Thor is likely needed to tie-in for Avenger 2, and the ladies all love Hemsworth.

Scarlett Johansson seems replaceable to me, though. Any busty actress in a red wig could fill her role of standing around with guns. And Jeremy Rener...I mean, does he even get a paycheck for these movies? He's practically the Aquaman of the Avengers. He could be Chuck Cunningham-ed and nobody would care.