Who gives a **** if he's had 6 movies, 10 years of exposure! Should they retire Batman just becuase he's been on film since the 40s, with atleast one movie each decade since? Same with Spider-Man, he's going to have almost 20 years of being in motion pictures from Raimi until Webb.
Another thing this has been the most popular Iron Man has ever been. From 1963-2008, Iron Man was in zero live action movies and tv shows, one decent animated series that only lasted one season, the one before it was abysmal, never took part in any major comic book cross over event (he was there for Secret Wars, but Rhodey was in the suit and made Iron Man look like a dumbass in the eyes of a lot of hereos there), never had his own video game, and pretty much took a back seat to most characters. He's now finally getting some spot light after all these years, has movies being made that the general audience is loving and finally has merchandise that people are buying, and they should just kill him off at the height of his popularity? Nonsense.