2. Mallen
It's widely acknowledged that Iron Man 3 is primarily concerned with the acclaimed Extremis arc, and so much of the film will likely be concerned with Iron Man preventing The Mandarin (Ben Kingsley) from spreading the Extremis virus worldwide. Fans of the comics will remember that The Mandarian had a lacky called Mallen, who injected himself with the Extremis virus and very nearly bested Iron Man once and for all with it. Given that we can see Iron Man controlling dozens of Iron Man suits in the trailer, it's not at all a leap to suggest that by this point Tony has injected himself with the virus in an attempt to try and bring both The Mandarin and Mallen down. Though Mallen probably wouldn't get more than the most supporting of roles, it'd be a nice nod to the comics. Perhaps his scene would come at the end of the credits; The Mandarin would be defeated, and the Extremis virus would presumably wiped out, except Mallen made off with one vial and injects it into himself as the curtain closes.