I have to agree that the man whose eye's turn from blue to yellow is probably Xehanort. Perhaps this is kind of a Star War type similarity. In the first movie, the text "Master of Xehanort" comes across the screen. Could that bald man be the man who was or will be his master.

I mean all we know of Xehanort is that Ansem found him in a critical state and that he has know idea where he came from.
-----------------------------------------------------------------------
So that's one thought. The other to consider if none of those people are who we think they are, then perhaps they're all new in a sense. So far we've discussed how Nobodies and Heartless are created. What we haven't discussed is what happens to the light in a person's heart. Could the three armored knights be light forms of those who fell prey to the Heartless?

It's a very long shot, but who knows where the story will go in this Kingdom Hearts.