Nothing is confirmed by the studio yet. These two stories have come out so far:
1. It is War Machine in his new upgraded armor.
2. Iron Patriot is the main villain, with (reportedly) Mandarin backing as a secondary villain. He will be a mix of tow villains like Vanko(Crimson Dynamo) and Whiplash, in the second. The man in the suit is Coldblood, the cyborg, taking the place of Osborn.
I guess we will see as it get closer to release and the trailers hit.