They are new characters and on a side note, Nomura also stated they were picking up Riku's Road/Way to Dawn, Mickey's Reverse Kingdom Key, and Sora's Kingdom Key.
Nomura Interview from the Ultimania Guide
Q. After the ending, there's a secret movie this time, too. What exactly is the movie trying to tell?
A. I actually have a solid idea on what the movie's setting will be in my head. In the previous game's secret movie, I wasn't even sure if I would be making a sequel or not, so some parts of it were quite vague. But this time I already have an idea my head where I think "This is it."
Q. Did that scene happen in the future or in the past?
A. I would at least say it's an episode in the past, but.... Hmm, how should I say this? It's in the past but you can also think it's in the future, something like that.
Q. Who are the 3 armoured people?
A. Those 3 are completely new people who haven't shown up at all. In fact, I've already thought of their names. Back when I was making that movie, I only had their settings but now I've even drawn their faces to give myself a clearer image of them.
Q. The king, Sora and Riku's keyblades were there, too.
A. It's to show that those three armoured people aren't them but that doesn't mean they don't have connections. The words "Keyblade War" that showed up in the middle were to implicate that there were fights between Keyblades. Most of the puzzles in the first KH have been solved in KHII but there are many things about the Keyblade that haven't been revealed yet. A line from the previous game's Ansem Report #8 appeared in the movie but that is to say "It means this but it's not explained yet."
Q. Does that mean you already have a plot for KHIII?
A. Hmm... I have an idea but it can't be helped because my team are planning to work on our next different title. So we're not working on KHIII now and we're not planning to work on it for some time, too. I have a plot in my head but I'm not sure if it'll be released to the world or just stay in there.
