Square Enix and Disney officially announced Kingdom Hearts 4 today during the franchise’s 20th anniversary celebration. The next chapter in the mainline series of the beloved action role-playing franchise will officially be referred to as "The Lost Master Arc," and will presumably pick up after the events of Kingdom Hearts 3.
If you haven't yet beaten Kingdom Hearts 3, which was the conclusion of the Xehanort Saga, or the Re Mind DLC that came after, then you may be a little lost when it comes to the announcement trailer. Sora awakens in the city of Quadratum, also known as Shibuya, which is a world located in another universe, or the "other side of reality." Unlike the worlds in the previous Kingdom Hearts games, it is foreign to both light and dark -- or so it was, it seems. As you see in the trailer, darkness seems to have infiltrated this world, and Sora's arrival may have something to do with that.
Kingdom Hearts 4 is still early in development, so it may be a while until we see more of the game. However, the little that is shown certainly looks impressive.
Not much is known about the game's story itself but as the series has ties with Disney, we can expect to visit various worlds inspired by the company's franchises. In the past, the focus has been largely on classic Disney as well as Pixar and Walt Disney Animation properties. But there's speculation Kingdom Hearts 4 could take us to Star Wars inspired worlds.
There's speculation that the world shown around the 4:40 mark is a Star Wars planet (potentially Endor) and that in the top right corner we see the foot of an AT-ST. This hasn't been confirmed, of course, but it certainly looks like it could be true. Star Wars has never appeared in a Kingdom Hearts game but as the franchise is owned by Disney, it very well could be featured. There's also hope that we could visit some worlds inspired by Marvel as well but there's no indication of that in the trailer.
No release date has been announced for Kingdom Hearts 4 but it's presumably at least a few years away. Platforms weren't annoucned either but we can probably expect a release on the PS5 and Xbox Series X|S and potentially PC as well.