Yeah, Giga Bowser...
I kinda like the idea of there being a battle of good versus evil in the story mode of the game. Yeah, the premise seems a little cheesy, but games like Kingdom Hearts showed it could work. Whatever this "force" is that's bringing them together (and I do think it's something bringing them together, considering those clouds) I definitely think it won't be "new" exactly, but something from Kirby's games, I don't think the emphasis on Meta Knight's ship is just for effect.
I'm going to make a prediction now: Dark Meta Knight and the Black Nebula. Ten bucks...