I haven't seen the film yet, so I don't know. But, from what I gather from the previews, it looks like he is a drunk (homeless?) superhero who sobers up when others (Bateman) confront him with the realities of his situation and who he is.
I can't see how that would hurt a possible "Stark falls heavily into alcohol (possibly based on a Pepper/Happy relationship, possibly based on an inability to stop the Mandarin, possibily based on fame and fortune going even further to his head), Rhodes takes over for him, then Stark has to battle personal demons before stepping back into the suit (with Rhodes possible standing in his way, with kind of a "Responsibility should only go to the responsible" mindset) before a final confront with Mandarin" storyline. Hancock seem to be a "drunk sobers up" tale, while Iron Man 2 would be more of a "man with a responsibility goes down a dark alley before getting his life back on track" story.