Vanitas isn't one since he rejoined with Ventus' Heart, which is now inside Sora's.
Actually, can we really be 100% sure about that or have we definite information from Nomura?
Because if this what you wrote really is true then
Ventus heart would be complete again AND he would have his own darkness back. But then there's a glaring plothole at the end cuz if Ven's heart had it's darkness back he shouldn't become comatose but a heartless...likely a shadow like Sora in KHI.
But I was always a bit confused about this issue with Ven's heart.
As far as I understood it, after Ven destroyed the X-blade his heart was fractured(injured) again just as it was in the prologue when he had his shirtless awakening on that broken glass pillar.
Except this time the injury was so severe that even the connection with Sora's heart couldn't keep him "alive" anymore, so, as a last desperate attempt, Ven asked to find refuge in Sora's heart when he followed the connection back to Sora's heart after Sora felt his deep sadness.
What happened to Vanitas though, I wonder, he disintegrated like Eraqus did and since the X-blade was made of both their hearts I assumed that Vanitas' dark heart was fractured(injured) just as Ven's was.
I found this chain of thought very reasonable and logical (in KH-Universe-terms), but maybe someone of you KH-comrades can enlighten me further.
As for Options who could be in league with Xehanort...don't forget Saix aka Isa.
Nomura hinted in one of his interviews that the yellow eyes and pointed ears have some deeper meaning...and Braig(Xigbar) isn't the only one who has them in the organization.
I'm also curious which role Maleficent and Pete will play in all this mess...
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As for the main topic:
Difficult, but I think either extensive preparations for the MoM or the MoM itself sounds quite reasonable.
On the other hand...if KHIII is all about rescuing the crippled ones and defeating Xehanort for good (if KH III really is the last game of the Xehanort Saga. As far as I remember Nomura only said one future game will portray the final battle between Sora and Xehanort, he didn't specify he meant KH III) it'll be a hell lot of work to do.
1. Rescue Aqua and AtW.
2. Rescue Ventus (not possible until 1. is archived) => they may also still need to heal Ven's heart if hearts doesn't have the ability to regenerate over time when they're asleep
.
3. Rescue Terra
4. Rescue or whatever they plan for Roxas, Xion and Naminè...
5. Defeat Xehanort's possible new (or old) allies
6. Defeat Xehanort himself.
That's lot of stuff to do and there are not even counted in new plans, intrigues or schemes Xehanort may devise to archieve victory for himself.
For example, if Xehanort would decide to try to wipe out Yen Sid, or use the new knowledge he earned through Xemnas (over the chambers of repose and waking) to completely whack up the plans of the hero side i.e. kidnapping Ven right under their noses when Aqua leds Sora to the CoW in C.O. to help them or some other nasty surprise...
Long speech, but damn lets get to the point...there's really much to do in KH III so they should at least know beforehand how they have to rescue everyone of the crippled ones and where to find the necessary parts for success of the rescue missions. (Especially regarding the whereabouts of the essence of Terra's existence!)
And that's the points I would assume KH3D and the additional mystery game would have to cover.