Terrence Howard will need to be in Iron Man 2, or else Continuity will destroy the entire Franchise. Show your support, and sign!
Two days later, this section was added for clarification:
Its obvious. You don't replace major characters in summer block buster movies. Just plain stupid
Well, that's a solid, well-written argument, except for that Dark Knight did replace a major character, and some would consider that movie both a blockbuster and not just plain stupid. Is that all you've got? Surely there must be more motivation for convincing Marvel to let Howard tkeep the role. Let's take a look at the webpage someone seriously made, HowardNotCheadle.com (via Latino Review):
Marvel is under the impression that just any person can play Col. James 'Rhodey' Rhodes. They are sadly mistaken.
Marvel asked Terrence Howard to be Rhodey. He signed on to play Rhodey. Terrence Howard became Rhodey.
We were under the impression that when you signed a contract with someone, it was their word.
Yeah! I'm just a guy on the internet saying things, but what about that contract I've never read! We had your word, I assumed!
Yeesh. It's time to accept that there's probably a legitimate reason Terrence Howard was dropped from the film (like how he says crazy things), and that Don Cheadle is now Rhodey. Like all other casting changes, you'll probably eventually be OK with it. Just think how we once thought Michael Keaton was the definitive Batman, but now when you hear "Dark Knight", you just think Val Kilmer. You'll get used to it.