So, I've been thinking...
Does anyone remember how Ansem the Wise, in Blank Points said, "He could open the right door, and save all those people whose lives I managed to ruin."?
And, obviously, we know that Nomura has said that the tormented are asleep and shall be reborn through that sleep.
Now, all this leads me to believe that above posts are correct, in that we'll probably see a majority of these people in the Realm of Sleep.
So, here's my theory: Sora and Riku are looking for the Keyblade of Sleep. I bet that'll open that door that Ansem mentioned, and more than likely, save a number of these people. Maybe Sora just needs to open the door, find the people, and return to the real world with them.
The only thing I can see against this theory, is that Nomura said no one would be rescued until KH3...