Just a quick theory.

[Fuse]

First one I've even been able to think of =).
Well, here goes nothin'.

I believe after watching the secret movie that the heart that appeared above was not Kingdom Hearts but instead the Heart of that World they were in.

And that the UEM is going to destroy it or manipulate it to his use OR to create complete darkness across the world or maybe there is a deeper meaning to it.

Also the knights are the guardians of this Heart of the World?

Remember don't flame me =/
These are just some quick thoughts of mine.

 

[Bops1234]

That's a possibility. You should fuse this with some other theories to make a mega-theory of your own. lol
But maybe.

 

[Fuse]

Idk.
My theory is more of just getting opinions from people.
so lets hear it people =)

 

[Keyblade Savior]

It sounds plausible.. I don't see how it couldn't happen that way.. nice theory.. I applaud...

 

[r0x45]

man thats a good theroy i think the only thing i have to say is that if i remember right that in TWTNW the big heart shaped moon was refered to as "kingdom hearts" and this same moon is seen in the secret movie

an nifty question is what is with all these keyblades like 1000's of keyblades just chillin

 

[Keyblade Savior]

r0x45..you're so gangsta......although I do agree with r0x45... why are the keyblades there in the first place?

 

[Gabranth]

Thats an interesting idea, ive never thought about that.

 

[r0x45]

keyblade graveyard where the many have fallen and the many are sleeping are born....."birth by sleep" anyone???

 

[OmniChaos]

keyblade graveyard where the many have fallen and the many are sleeping are born....."birth by sleep" anyone???

I think "Birth by Sleep" revolves around the "Room of Sleep" and the "Room of Awakening".
But, I do agrre with the part about a graveyard. Because that fight seemed to be almost the climax of the Keyblade War....

 

[Fuse]

What I'm trying to get at is that the Giant Heart is really the Heart of that World.

I'll explain.
Remember how the heartless in the first KH were going into the hearts of the Worlds and causing chaos within?

I think that the UEM had the power or knowledge to summon the heart of that world.
So, the point being that he would use it to bring ruin to the World or Worlds.
Or manipulate it to gain power over the world.