Surprisingly, the official trailer for Kingdom Hearts IV during the event for the twentieth anniversary of the series (we told you about it here). During that event, Tetsuya Nomura revealed that Kingdom Hearts IV was chosen over another game.
The announcement of Kingdom Hearts IV surprised the entire gaming world and was also revealed through a gameplay trailer which sees the return of Sora in the world of Square. However, some statements coming from Tetsuya Nomura, director of the Kingdom Hearts series, suggest that there was a bit of indecision around the title.
During the event for the twentieth anniversary of the saga, Tetsuya Nomura stated that initially he was undecided whether to make Kingdom Hearts IV or a different game. The title would have seen Sora as the protagonist, but it would have been linked to the world of True King, which is an existing video game in the Kingdom Hearts universe, introduced in Kingdom Hearts III.
Within the series, Verum Rex would be a Square Enix game for Play Plus, which is a parody of the PlayStation, sold inside a toy store in the world of Toy Story.
In addition, many of the ideas seen in Verum Rex are based on Final Fantasy Versus XIII, Square Enix title finally became Final Fantasy XV. A game trailer in Kingdom Hearts III resembles the one in Final Fantasy Versus XIII, with the protagonist reminding Noctis very closely.
However, Nomura has decided to opt for Kingdom Hearts IV development since it would have been too difficult to work on two games at the same time. In addition, the Game Director knew that many fans were concerned about the fate of Sora, whose whereabouts had remained uncertain at the end of Kingdom Hearts III.
So, Kingdom Hearts IV is finally a reality and the title will reveal Sora's fate. In this regard, we refer you to an article in which we talked about the change of look of the protagonist of Kingdom Hearts IV.