When Xehanort is answering Sora's question "Enough, why are you doing this?", Xehanort gives some answers that I believe are more revealing then they initially seem...

 

*Sora (whether this was intentional or not on Nomura/Osment's part is TBD) sounds nearly as if he was pleading to Xehanort like it wasn't the first time he's seen something like this happen, making me wonder if Xehanort/Organization 13 intend to knock the balance out of the Worlds by running what seems to be a experiment if not a full blown out plan of dividing Worlds in two and turning characters throughout to Darkness.

 

*Xehanort says aloud that he wonders how Sora will "handle the strain". Given that by this point I suspect it's all but confrimed that Xehanort wants Sora to give into Darkness and is actively pursuing him doing such, this seems to be the overall plan of attack on Sora. Watch people suffer as the Organization splits Worlds in Two and reeks havoc by unleashing Darkness, not only unto the World's themselves but individuals as well.

 

*It's mighty interesting that every single variant of Xehanort is so singularly focused on Sora.. I wonder if they have a deeper connection then we've thought. Young Xehanort was living in Destiny Islands before he was found by his older self after all..

I'd like to think that they know of all the pain that's inside of Sora's heart. Don't forget that Namine said to Data Sora that he might not be able to handle the pain that's inside when it's time to save them. He had to have been alluding to that when he says "a train.

 

As far as it not being the first time it's happened, i'm sure it isn't. You know how Kingdom Hearts characters like to announce peoples appearances by name or "You?!". If this was our first time seeing YX in KH3 then i'm sure someone in the room would've called out his name.