This page contains unmarked spoilers from all previous games. You Have Been Warned!
There will be a framing device with King Mickey
Leading off from the ending of Melody of Memory, Mickey will be there learning about the world’s past and uncovering vital clues for IV.Quadratum is our world
If the information about Augmented Reality is correct, then the Quadratum our characters are traveling to could be our world.- The artwork of Quadratum on the KH3 cover art shows a clock with 13 numbers meaning it's on a 26 hour day/night cycle. If this remains the case going forward then its not going to be our world which is on a 24 hour day/night cycle. Though it is likely still the KH equivalent of our world.
Heartless that could appear in this game
Pureblood:Emblem:
Luxord's and Demyx's somebodies will be introduced
Since Lauriam and Elrena were introduced KHUX.Sigurd will travel through time and/or become immortal
Sigurd narrated the Kingdom Hearts 4 trailer and it would be strange if the trailer's narrator didn't appear in the game. However, Sigurd lived at least 100 years before the events of Kingdom Hearts 4, so he would have to do 'something' in this game for that to be possible.