DDD
Sora:What are you saying that he knew everything that would happen?
YX:No not everything....but remember Ansem possessed Riku and saw his experiences in real time
Sora:So that could only tell him so much, how did he know I would be here today?
YX:Simple....
*BOOM*
Sora:Kairi!
*Kairi flies into Sora*
*Weird staby sound effect and Sora sinks back into sleep*
The it transitions over to the scene about how Sora had been to Traverse Town many times, again and again like deja vu. Oh...
I think you're reading a bit much into that. 3D's destiny schtick seems pretty easy to explain the way Doctor Who does it in The Angels Take Manhattan -- once you've lived an event, you can't change it. By living certain events via Riku, Xehanort "fixed" them in his personal timeline, which is the timeline the narrative is choosing to follow (given that this and Doctor Who both kind of assume that there are characters whose PoV "matters", and would thus fix an event).
It's kind of a new agey misunderstanding of the observer effect and Schroedinger's Cat, along the lines of -- once you see it, it's set in stone. If Ansem hadn't possessed Riku and hadn't observed the effects, to him it would still be "possible" for those events to differ than what we ended up seeing, but because he observed them they are locked.
The Traverse Town scene is simply that...Traverse Town is where everybody goes. If you want to make sure you'll find someone at a certain time, go there. Once you reach a "version of yourself" at that point in time, you can then travel around that period in time (like Sora and Riku do, allowing them to enter the Realm of Sleep), and presumably do research and stuff to figure out where they were and where they would be. This implies that Xehanort went to the real Traverse Town at some point, and started surveilling Sora, either through simply spying, or by planting something in him like with the Recusant's Sigil -- from there, they very carefully guide him toward ending up at TWTNW in the Realm of Sleep, and once they're sure that Sora will definitely not escape their grasp, YX shows up there to "observe" Sora being captured, and make it a destined event (possibly, if they had done a worse job at manipulating Sora, he could have sidestepped TWTNW, and when YX showed up there without Sora, it would instead make it destined that they DONT capture Sora). Going out on a limb here, but presumably Young Xehanort is going to be present when the X-blade is finally constructed, and he seemed ---awfully certain--- that Sora would be in their number -- you'd presume he'd be able to sense who counts as a "version of himself" that he can use to travel through time.
In other words -- what if Sora's been designated a vessel ever since the first time he went to Traverse Town?
Basically, I don't think we need to posit some mystical power to "sharing eyes", when it can just as easily be explained as your standard pop culture version of Schroedinger's cat, just what it appears to be on the surface. I mean, it is Nomura, it's always possible he goes off on some crazy retconning tangent, but...I don't see the need to assume that's what he's doing at this point in time.