Kingdom Hearts 4 is in development, and a trailer has shown Sora, Donald, Goofy, Luxu, and a recently introduced character named Strelitzia. Other than these characters and the world shown in the trailer, much of what is in store for fans is unknown. Kingdom Hearts 3 wrapped up the stories of many characters like Xehanort, Roxas, Ventus, and others, meaning new stories are on the horizon.
With new stories and characters coming, some old faces might be left behind. Fans are also likely wondering what Disney characters and worlds may await. One can only make educated guesses, but there are some characters that likely will not appear in Kingdom Hearts 4.
Characters That Won't Likely Return
Fans are not expecting Ansem the Wise to come back. He had connections to Xehanort's story, and now that Xehanort is taken care of, Ansem the Wise has little reason to be involved. He does appear in Kingdom Hearts: Melody of Memory, but only to study memories in Kairi's heart to find out where Sora may be. Outside of studying the heart, he does not have much skin in the game anymore.
For the same reasons, Xehanort is not likely to appear. If he does, it will likely just be in flashbacks. Like Ansem, he does make an appearance in Melody of Memory but only as a sort of ghost. Kingdom Hearts 3 provided a good conclusion to his character and story, so the series will likely move on from him. Similarly, Eraqus is another character whose story seems done. He died along with Xehanort, but not without apologizing to Terra, Aqua, and Ventus for the trauma he caused them.
Vanitas also seems to have no place in Kingdom Hearts 4.He was the embodiment of the darkness in Ventus' heart, but he was defeated in Kingdom Hearts 3 and likely will never make a comeback since Ventus' story wrapped up. He did appear in Kingdom Hearts 3 Re Mind, but that was just as a data recreation, rather than the real person.
Lastly, there are certain members of Organization 13 that may not appear. These include those that were eliminated in Kingdom Hearts 3 -- Larxene, Luxord, and Marluxia -- as they were defeated and then not seen again as non-nobodies.
Square Enix And Disney Characters That Likely Won't Appear
Fans have gotten very excited in guessing what Square Enix and Disney properties may make appearances in the next Kingdom Hearts. Among these guesses are more recent Final Fantasy games, Marvel titles, and possibly even Disney shows like The Owl House. Based on what Tetsuya Nomura likes, what is popular in Japan, and Kingdom Hearts' history with franchises, one can expect certain things to make it into Kingdom Hearts 4.
Many fans do not expect characters from Final Fantasy 15 in a Kingdom Hearts game, as Nomura had to step down as the director of that game. There are a lot of rumors that Nomura may not have been pleased with this, especially when he put Verum Rex in Kingdom Hearts 3, like a teaser to his original plans for Final Fantasy 15 that were ultimately changed.
There have been ideas from fans about Disney shows becoming worlds in Kingdom Hearts, but that is also not likely unless the shows are incredibly popular in Japan. This means characters from The Owl House, The Lion Guard, and Miraculous: Tales of Ladybug of Cat Noir are not likely to appear, even as summons. If a show was picked, it would most likely be DuckTales, since Huey, Dewey, and Louie have already appeared in previous Kingdom Hearts games.
Kingdom Hearts 4 is in development.