Could Ven be in this "world of sleep?"

[leonidus]

Well, not impossible. The Re:Coded ending implied they found Ven's heart, Yen Sid takes them there (although you'd have to wonder why he wouldn't say anything), Neku seems to know Sora which means he might have met Ven in one way or the other and shared a word or two. Considering Ven's heart is "sleeping" in Sora, you see where I'm going with this.

What do you guys think, will we see Ven?

 

[Mirby]

It is a possibility, but I don't think so. I think the Realm of Sleep is there to test Sora and Riku...

EDIT: Also, here's that exact line, courtesy of my transcription.

Mickey: Yen Sid! I think we're finally getting close to figuring out where Ven's heart is!

Yen Sid: Is that so? Then that leaves only Terra.

M: Right! And we've gotta save all three of 'em!

 

[loke13]

Sora's heart is in Ven :/.

 

[Sephiroth0812]

Mickey has a pretty good idea where Ven's heart is according to how he words it to Yen Sid, but he isn't completely sure yet.

The MoM-exam is said to be only a portion of DDD while the rest focuses on the data Ansem the Wise hid inside Sora which is said to be the "key" to saving the tormented people later in KH III.

It's quite possible we'll get some information on Ventus as well as some of the others in torment.
Ven's heart is asleep inside Sora because of its horrible injuries sustained by the destruction of the x-blade, so while I would doubt we'll see much "active" stuff from Ven's side the information we will most likely get is the current state of his heart, Sora will finally become aware of the fact that he's protecting the boy inside him for almost 11 years now and Mickey will probably get the final proof that Ventus's heart is indeed there where he thought it is.

As for Ventus himself being "active" and able to talk that would depend on if his heart managed to recuperate to a degree, considering Data-Naminé in Coded mentioned that she could not access the tormented memories she found inside Sora and also advised highly against it because the pain is so horrible there's also the danger of damaging Sora's heart.

 

[Mirby]

Mickey has a pretty good idea where Ven's heart is according to how he words it to Yen Sid, but he isn't completely sure yet.

See the dialogue above.

The MoM-exam is said to be only a portion of DDD while the rest focuses on the data Ansem the Wise hid inside Sora which is said to be the "key" to saving the tormented people later in KH III.

AtW: While the boy slept his long sleep, I hid the results of my research inside him, transplanting the data to where it might best serve a purpose. In fact, I would like to believe... Maybe he can set things right. A boy like him who touches so many hearts- he could open the right door, and save all those people whose lives I managed to ruin. So many are still waiting for their new beginning, their birth by sleep. Even me... and even you.

It's quite possible we'll get some information on Ventus as well as some of the others in torment.
Ven's heart is asleep inside Sora because of its horrible injuries sustained by the destruction of the x-blade, so while I would doubt we'll see much "active" stuff from Ven's side the information we will most likely get is the current state of his heart, Sora will finally become aware of the fact that he's protecting the boy inside him for almost 11 years now and Mickey will probably get the final proof that Ventus's heart is indeed there where he thought it is.

As for Ventus himself being "active" and able to talk that would depend on if his heart managed to recuperate to a degree, considering Data-Naminé in Coded mentioned that she could not access the tormented memories she found inside Sora and also advised highly against it because the pain is so horrible there's also the danger of damaging Sora's heart.

Yeah, that makes sense.