I read some of the posts and I see that the discussion has shifted substantially to more about the Ventus/Vanitas dynamic, but back on with Vanitas being a villian:
I sort of assumed he would be one of the Thirteen Darknesses, and I hope that's the role he plays. I assume he'll come back (since he made extremely brief cameos in 3D). Vanitas works better as an underling because he's had no development. But, I suppose that's what they were going for, considering Vanitas is "pure darkness" anyway.
Development is only one part of the thing though. For example Emperor Palpatine when first introduced in Empire strikes back and later Return of the Jedi also had close to zero development (and he didn't get much during the original trilogy beyond "evil overlord") and yet he is still the main villain.
I agree that Vanitas works better as an underling, mainly though because of how his character and personality (the few bits we know so far) works. He has neither the charisma, cunning or a different trait that would paint him as a leader figure. On the contrary, he's not only vain, brutal and cruel, but also brash and impulsive bordering on recklessness sometimes.
From an outside point of view, I do not see why anyone would be willing to follow him or accept him as a leader.
He'll most likely be one of the Darknesess and while I think it's be nice to get more development on him, he runs into that issue that if he's included in KH3 there simply wouldn't be much room without half-assing it. So he probably will remain an underling till the end.
Presuming that Vanitas does survive until the next saga though, if they want to continue building him up as a villain, the story could revolve around his slow rise. I can't see it happening it, but hypothetically speaking, the next saga could be the "Vanitas Saga" and where the Xehanort Saga is about a villain who already left a big footprint, the next one could feature the villain just getting their start and attempting to make an even bigger one.
That's why I expect only some tidbits and/or small cutscenes involving the other main characters, mainly Sora and Ven, but ultimatively there won't be much central focus on him. All in all, Vanitas works better as an underling anyways as turning him into a leader figure could be done only with a totally abrupt 180° turn in the current setup.
This is exactly what I would expect as well considering the current setup of Vanitas as a concept/character. He
can become a main villain over time, but that would need some fleshed out buildup so that he realistically could emerge as the primary villain only about halfway into the next saga, possibly with a different "arc-villain" taking the place as "main threat" for the first half of the saga, either a new character or let the Disney villains take that role.
Of course Vanitas would also oppose the heroes during the first half of the saga, but no one would actually see him as the main danger yet.
I don't think there's ever been a clear shot of Vanitas' ears. They are always obscured by his giant sideburns and the metallic piece of his helmet.
I believe everybody has a reason to beat the jam out of Xehanort, considering that they all have been wronged by him one way or another. However, I think the one who will deal the final blow would be Sora, and it would be representative of the "revenge" exacted by all those people because of their links to him.
Yep, Vanitas' ears were never visible because they're completely covered by that metallic jaw-piece from his helmet.
Even without it, the hair would still be in the way as shown when looking at Sora who has the same hairstyle, since while his ears can be
seen, it's only the lower half and thus if the tip is pointed or not would be impossible to see.
Either that, or they will blow him apart with a combined team-attack either from all directions or channelled through Sora.
That there are so many who have to pluck a crow with the old coot is one of the reasons why I think that it would be unfulfilling to have just one person deliver the final blow on him.
If Sora is the one to do it, one part of the fandom will be upset because it's the typical "main protagonist gets all the best parts"-schtick and because there are people who have suffered more under him,
if Ven would be the one to do it, there would be accusations of "stealing the spotlight from Sora" or that "Terra deserves it more", same goes for if Terra, Aqua or anyone gets the honor yadda yadda, you get my drift.
