English trailer for Dream Drop Distance!

[Mercen-X]

By the way, I'd wager that Xion will be revealed as (SPOILER)another member of Organization XIII 2nd

How so?

Well (SPOILER)in Days, Xion was "apparently" meant to clone the abilities of the keywielder Roxas. But Xehanort himself was a keyblade wielder, so Xemnas's interest in the keyblade may have been subconscious. In other words, giving Xion the ability to wield a keyblade made her an ideal candidate to serve as a vessel to Xehanort. Personally, I'm a little confused why Xeha bothered with Braig or Isa.

My other guess would be the Riku Replica and no (SPOILER)he wouldn't be dead or heroic if "Young Xehanort" time-traveled to obtain him.

Personally, (SPOILER)I'm still not seeing how "Young Xehanort" is not "Terra-Xehanort". While it's true that Riku took Ansem's form to battle Sora and then to save him from O13, Ansem was still just a version of "T-X" whereas "T-X" is the only cited possession to result in a being's physical appearance being altered (and that being limited to the color of his hair). Aside from taking on Ansem's form altogether (and a version of Vanitas's outfit), Riku never showed any physical transformation. Perhaps this is because Xemnas still existed which could possibly explain also how Xigbar and Saix (also vessels of Xehanort) showed no signs of transformation either. We're never told where Terra is originally from and we're not shown the timeline for which Young Xehanort dwelt on Destiny Islands so two possibilities arise. Either YX is a young version of TX (like Young Sora and Young Riku) or Terra himself is a paradox being at once both the vessel for Xehanort and the eventual time-traveling old Master Xehanort who would come to possess Terra. Where the latter option leaves YX, I'm as of yet still uncertain.

I'm also still curious how Vanitas fits into this mess.