Kingdom Hearts 4: 15 Disney Worlds We Need To See
3. The Avengers (2012 NYC Location)
Whilst Guardians of the Galaxy and Black Panther would make for great Kingdom Hearts worlds if any MCU property was going to be added to Kingdom Hearts IV it would be The Avengers.
There is a lot that can be done with an Avengers world. The world could be an adaptation of the first movie with the addition of Sora and company, the world could take a single segment of the movie like the Battle of New York and adapt that, or the world could tell a completely new story that takes place after the original movie.
The last option is probably the best.
Running around New York to assist the Avengers in taking out various comic book villains to become an honourary Avenger could be a lot of fun.
The world could always have one overarching story, but imagine a world filled to the brim with smaller missions where you team up with different Avengers depending on the mission. It would lead to a lot of fun variety.
Imagine a stealth operation where you have to team up with Black Widow and Hawkeye, or a mission where you have to fight a really powerful threat so you partner up with the Hulk and Thor.