Robert Downey Jr. revealed in April that he wants to retire the Iron Man character. However, in June, the actor signed on to reprise his role as Tony Stark in both The Avengers: Age of Ultron and The Avengers 3, so it is unlikely that his character's death is imminent.
There are already franchises based on Chris Hemsworth's Thor and Chris Evans' Captain America, so who does that leave, without a franchise attachment? Mark Ruffalo revealed in March that Marvel doesn't have any plans for a stand-alone Hulk movie, and there are no franchise plans that we know of for Jeremy Renner's Hawkeye and Scarlett Johansson's Black Widow. Could The Avengers: Age of Ultron include the death of one of these heroes? We likely won't know until this sequel hits theaters on May 1, 2015.
Avengers: Age of Ultron comes to theaters May 1st, 2015 and stars Aaron Taylor-Johnson, Scarlett Johansson, Robert Downey Jr., Elizabeth Olsen, Chris Hemsworth, Chris Evans, Cobie Smulders, Jeremy Renner. The film is directed by Joss Whedon.