Good news to the fans that were worried about Robert Downey, Jr. not returning as Tony Stark / Iron man, today Marvel Studios announced that he has signed a two-picture agreement to reprise the role in Marvel’s The Avengers 2 and Marvel's The Avengers 3.
Joss Whedon right now is in the process of scriptwriting "Avengers 2" which will start production in March 2014 and will be released on May 1, 2015.