Sorry if this has been said already(I didn't read all of the thread/skimmed over it), but I'm thinking that in the KH world, the "Dream" and the "Drop" are similar, but opposites. Dreaming is like you're falling into the non-physical world, and dropping is like you're falling into, or in, the physical one. Maybe this "switching" Nomura mentioned was like going between the two worlds, and that's why he announced that the game was going to be a mindf*ck; which events actually happened in the physical(drop) world, and which ones were illusions(dream world)? Maybe that is the test for Sora and Riku; maybe in the dream world, one of them turns against the other and actually thinks it really happened, then that said person gets back to the physical, and starts to distrust that other person. Maybe that's why, in that picture with the two set against light, they cross blades. I think the "distance" part is A.how they need to seperate/distance the real from the fake, or B.how far they fall into either one of the worlds.
Like, this is how it is in the beginning of the game:
Dream World=Physical(drop) World/IDK what the heck is going on
And then Yen Sid wants them to learn that:
Dream World-----------------------------------Physical(drop) World
Maybe that's kind of a confusing example. But remember the beginning words of each game?
I've been having these weird thoughts lately. Like, is any of this for real, or not?
Real=Drop/Physical World, Not=Dream World
KH2:A scattered dream that's like a far-off memory. A far-off memory that's like a scattered dream. I want to line the pieces up; yours, and mine.
Dream- something that did not happen in real life, but in your unconscious mind.
Far off memory- something that happened in the past of the real world.
It seems that the line from KH2 is saying that, if it's actually Sora(which I'm sure it is, judging by the voice), that he's confusing the two:memories and dreams. Usually, at least in our world, dreams are not considered real. Memories are. Nomura has said(I think) that this game is about the connections between people? Sorry if I'm wrong, it's been a while since I thought /read about 3D. We've seen in KH that people can be connected through memories, but maybe they're also connected through dreams. Maybe that's really the way Xion and Roxas received Sora/Riku's memories-by making a connection through dreaming. I mean, did Nomura ever explain why Sora HAD to be asleep while his memories were re-aligned? Maybe that's why-Sora had to be asleep to receive memories, like Xion and Roxas, because being in a state of sleep makes it easier to connect to people.
Think about Sora when he was just born as a heart. Technically, it was still sleeping, and Ven's was just on the verge of sleeping/disappearing. Through this state, Sora was able to connect to Ven and pretty much save his life. So, it might be possible that Yen Sid wants Sora to learn how to navigate between the dream world and physical world, so that he might be able to follow his connection to Ven's heart through sleeping, and either wake him up or just figure out where he is. It's possible that, at the end of 3D, Sora finally figures out where Ven's heart actually is. I assume this might make his crap his pants. And if the theory that Riku is harboring Terra's heart, as well, Riku could use this technique to reach to Terra. The "Drop" gauge (I think that's what it's called) could deplete over time, and then they switch between worlds/characters.
IDK, just some ideas.