I thought his Mandarin worked well for that movie. Iron Man also seemed to play the loosest with its villains of all the Marvel movies. It was a good twist. It allowed them to continue with the themes they've always had. A generic terrorist (or Chinese stereotype) would not have worked as well.
But I'm looking forward to see what they come up with. Ben Kingsley did a great job with that role. I could see him encountering the 10 Rings organization, who is angry at him for stealing their imagery. Alternatively, it could just be a light-hearted scene - particularly if it's a one shot (I doubt they'll use that to reveal anything significant). However, if it's for Agents of SHIELD, it could be a major plot point.