Before people read the title of this thread and begin to comment saying "LOL UR STUPID MF = YX NAMURA SAYS IT", read this entire thread please.
Now, how did I come up with such a claim? The ending of the Jump Festa trailer had me thinking. Why exactly did Vanitas appear? Here is my explanation:
Lets jump back to the BBS Final Episode. Terranort unlocks his heart, creates the Guardian. There was an interview with Nomura (I think in BBS Ultimania, cbf to look) where he said the "fixed sentient left behind was not a Heartless". BUT he did not say it was not a Nobody. What does this have to do with anything though?
Well, assuming that the heart that was unlocked/fell to darkness was MX's, I believe that a Nobody was created as well. But since it was his heart, his body he left behind at the Keyblade Graveyard could be this said Nobody. But again, how does this tie to anything? Let's look at Ventus' story
It is known that death is not possible in KH. When Ventus defeated Vanitas, he lost his heart in the process blah blah blah. But does this mean Vanitas' heart was destroyed?No. Like Ventus' heart, it looked for shelter, probably for the closest thing to it. And what do you know, MX's body happens to be available! In the same area as well! Coincidence? I think not. Is this still not enough to convince you? If not, I still have more to say.
Remember that thing called the Lingering Spirit (Vanitas' Remnant, etc etc etc). Remember the name of the Keyblade he has? "Void Gear"? A gear, obviously is apart of a clock. MF is known for time travel. Coincidence? I think not!
And here is my final point. How else would MX/Xehanort appear young again in the first place, unless he either changed bodies again or gained the heart of a young person (Note: Vanitas was around 15-16ish during BBS)?
One more thing to add. During the battle again MF in BBS, it is noted that his attacking style is similar to Ventus'. If none of this says anything, I must be batshit crazy.
Also, to those with good ears:
http-~~-//www.youtube.com/watch?v=JwOrv8CQuU8
If you listen closely to this song, you will hear the ticking of a clock at one point. I heard it around 2:25-ish
Anyways, that's my theory. Comment, criticize, etc, but no flaming.