The comic ends up with Tony injecting Extremis into his own body.
Feige: We go in a different direction than the comic. In the comic he goes, here's this body-altering device, I have to alter my own body and fight it. That's not an option here for Tony.
Black: The suit's in his bones now in the comics.
Feige: We didn't want that. We wanted to see how this fragile human being deals with all the craziness of the Avengers and Extremis and conquer it, rather than succumb to it and become something else. The minute he becomes a robot, he's not Iron Man anymore.
Black: We didn't want him to become a cyborg because he actually... it's the wrong way to go because he desires it in the comic and does it. The more interesting thing is if the temptation is there and he rejects it and he doesn't go to that crazy place. That's what a villain would do, a villain would say 'I want to be a god!', and suck it all into his bones. Tony would say no. This one is more mechanical and less biological.
Feige: In the comics 40 years into his run, you can do that, ok. Knock on wood, in part 12 there may be a suit coming out of his bones, but not now.