Xehanort has been the main villain plaguing the world of Kingdom Hearts all the way to the end of the Dark Seeker Saga. With how much of an impact he has on the series, it is very possible that his actions will affect the events of Kingdom Hearts 4 as well. Xehanort's actions affected the entire cast as well as the many worlds, so when players saw the initial trailer of Kingdom Hearts 4, it raised some questions about how Xehanort could still be involved.