Update: Just hours after appeariing on the Ellen Show, RDJ went on Letterman where he specifically denied that IM4 had a script or was in development, so go figure.

Robert Downey, Jr., whose current contract with Marvel covers just Avengers: Age of Ultron and Avengers 3, apparently confirmed that he will appear in Iron Man 4.  After denying any involvement for months, Downey, Jr. raised the possibility of doing Iron Man 4 in a recent interview with Deadline saying that his future as Iron Man "was being talked about on a number of different levels now."
 
Now, during an interview with Ellen Degeneres on The Ellen Show that was taped today, Downey, Jr., after first noting that "negotiations" were happening, finally admitted under Ellen’s prodding that Iron Man 4 was going to happen.  The actor did not specifically say that he would be playing Tony Stark in IM4, but that certainly was the implication, and given Iron Man 3’s $1.2 billion worldwide gross, it is hard to imagine either the studio or the star walking away from this cinematic gold mine.  
 
Downey, Jr. also noted on Reddit that “sooner rather than later the Marvel roster will be made public and all questions will be answered.  Until that time fans will likely be hanging on the star’s every word when it comes to their favorite superhero movie franchises.