Because he was considered a more bankable star at the time, Marvel Studios actually paid Terrence Howard more for his role in Iron Man than they did lead star Robert Downey Jr. Unfortunately, his stint as Colonel James Rhodes didn't last particularly long because when his demands weren't met for the follow-up, he walked away from the franchise and Don Cheadle later ended up replacing the actor.
During a recent interview, Howard was asked about a possible return to the Marvel Cinematic Universe and he didn't shy away from making his feelings clear. "You know what’s so funny? Even though I love Don Cheadle so much and I love what he’s done, I still hear a lot of fans asking, am I going to come back and be War Machine," Howard claimed. "Am I going to come back and be War Machine? I think they could have a huge franchise off of it, but f**k ’em." So, that's very loud and clear no from him!
While the actor clearly believes that his return to the role of War Machine would spawn a new franchise, it's unlikely Marvel would want him back, especially as Cheadle is doing such a great job!