Additionally i wonder if they will use this movie to start up the alcoholism character aspect of Stark. It seems he's really torn up mentally after the Avengers movie and he always was quite the drink guy in the movies so it would be a good opportunity to lay the groundwork of Iron Man 4 if it will happen (and i guess it will even if Downey gets sick of the role which he's not even hinted at.. he seems to enjoy Tony Stark).
I don't know. I know it's an iconic part of the comics, but I think it's probably TOO serious a topic for a big budget superhero movie to tackle.
Audiences still want to laugh and have fun
with this character, and it'll be kind of hard to do that if he's a sad and pathetic drunk lying to everyone around him like Denzel Washington's character in Flight.