While speaking to Vanity Fair during Ender's Game's promotional Tour, Sir Ben Kingsley was quizzed about
his previously teased, upcoming secret project with Marvel Studios
"I think it may be seen as . . . sometimes [Marvel] tacks on a short film to one of their other releases, maybe on a DVD or something. I haven’t heard anything at all about this. So it’s in progress. It will have to remain under wraps. Marvel was so brilliant in the way they kept the transition from the Mandarin to Trevor Slattery in Iron Man 3. They were absolutely brilliant at it. I so respect the way they dearly want to surprise their audiences. But we will just have to leave it in the realm of rumor."
So not much is confirmed, but it appears that his involvement will in fact be a One Shot of some sorts. Whether this will be placed on the 'Thor: The Dark World' Blu Ray or a future Marvel project remains to be seen.
Iron Man 3 is the fifth highest grossing film of all time and was released on DVD and Blu Ray on September 24th, 2013.