From what I stated in my "My Overall Theory" thread, Vanitas was destroyed, we know that. When something is destroyed in Nomura's concept, there is no death, there is only sleep. Vanitas is sleeping, the Young Xehanort at the end of the trailer we see is the real Xehanort. He has been sleeping, and since Vanitas originally was created from him, they are now in one body sleeping together. Yes, Xehanort and Vanitas are sleeping together. lol. They are waiting to be reborn since Xehanort became a Heartless. Now that his Heartless and Nobody are destroyed, they are now sleeping and he is awake. The reason I think he is still in the Dream Realm is because he is trying to fully separate him and Vanitas, so that he can bring back the Unversed and/or try to bring back his other forms.
Wut? I think you either misworded or misunderstood something there (bolded part).
Vanitas was not created from Xehanort, Vanitas was created from Ventus, to be specific, from a shard/piece of Ven's heart that was cut off by Xehanort and then became the core of Vanitas's heart.
Of course Vanitas was destroyed, Ansem SoD and Xemnas were as well...so it is not unlogical that they all show up.
What is not completely logical however, and what we have discussed for long here is the theory of the OP that Xehanort and Vanitas have a heart-connection like Sora and Ven have.
Vanitas being now in the RoS is plausible...that he's latched onto Xehanort without a connection however is not so plausible. Normally, he should be roaming the RoS on his own, not attached to Xehanort. If he IS attached to Xehanort due to his heart being totally crippled like Ven's (hello x-blade destruction!) then it has to be explained why Vanitas's heart then found refuge with Xehanort if there is NOT a previous connection between them.
Actually in theory Sora spawned two nobodies,Roxas and namine.He just doesnt have two nobodies because he is one body.Now a body with more the one heart within that turns heartless could in theory create more than one nobody.As for the Vanitas thing,Vanitas is the darkness of Ven and one cannot exist without the other.So as long as Ven is around so is Vanitas.As for him being inside YX,They are in the realm of sleep so you cant count anything out until the RoS is explained.
It were Sora that spawned Roxas and
Kairi that spawned Naminé, and if we go technical Naminé isn't even a nobody...not even DiZ knew what type of being Naminé really is.
So the theory would be that a full person with more than one heart within could create one nobody and x beings of the "Naminé"-type, with x being the number of additional hearts there is no body for.
That in Sora's case there wasn't a third being has to do with Ven's heart being a crippled train wreck.
Going by that, Apprentice Xehanort should have been able to spawn 3 beings. One nobody (Xemnas) and two "Naminé"-types since he held the hearts of MX, Terra and Eraqus.
They apparently CAN exist without one another...or why do you think Vanitas was so confident the first time he fought Ven when he tried to destroy him in BBS?
If Mickey had not intervened then Vanitas would have toasted Ven right there.
Anyhow, I agree that we need more information on how the RoS really works, who that young Xehanort really is and what Vanitas's presence actually is as well.
We're just speculating around here without actually having a single clue what YX and Vanitas there actually
are.