So that theory going around where Sora has amnesia in this game has a lot of weight since he doesn’t recognise Donald and Goofy, or Riku in a way where he’s surprised and happy to see them in the trailer as you would expect him to.
Technically this would be Sora’s first rodeo with amnesia since in Chain of Memories, he was actively getting his memories replaced rather than losing it entirely. In KH4’s case, losing his memories entirely would be a turning point for his character because would he still be the Sora we know and love? Or will he be a new version of Sora where we will see layers of his personality that we haven’t seen before because when he was getting his memories replaced in CoM it brought out a more irritable side of him.
This would also be in line with Nomura’s comment in making KH4 accessible to newcomers because it puts them into a fresh perspective like Sora will have in KH4. Meanwhile us old heads know everything that’s going on lol