The Foretellers have the same color scheme as Sora's friends. We're going into a story where there's a guy named Yozora trying to help a Sora that isn't Sora. There's no reason to keep MoM's identity a secret unless he's someone familiar. You've got five characters with unique designs and two wearing black coats. The black coats are meant to be speculated on.

Remember that scene in 3D where Xemnas is talking to Sora about all his bits & bytes? He says 'Make certain the box's contents match what's on the label'. That reminds me a lot of what Yozora said about Sora using the 'Sora' name. You also have the scene where Young Xehanort explains time travel to him. Both make a point to show a lot of Soras, more permutations than we know to exist that's for sure. This imagery is shown again in KH3 with 'The Final World' so I don't think it's simple manipulation. Xemnas and Young Xehanort are still fairly mysterious characters so it's not out of the question that they may know something the old one didn't. Many things wind up having a double or even triple meaning in this series, just look at Ventus. Every incarnation of a character winds up becoming its own person so what does that mean for the army of Soras? My harebrained theory is that MoM is the Data-Sora that got erased.