It took well over a decade after the release of Kingdom Hearts 2, but the long-awaited Kingdom Hearts 3 finally launched at the end of January 2019. Earning strong sales and critical acclaim, Kingdom Hearts 3 continued the franchise's tradition of complicated storytelling featuring a dizzying number of characters and plot threads.

To its credit, Kingdom Hearts 3 makes an effort to wrap up some of the storylines that have existed since the first game, effectively bringing the Dark Seeker Saga to an end. In order to keep the wildly successful franchise going, some new plot threads are conjured up in Kingdom Hearts 3 to be explored in future installments, with the game's endings giving fans some clues as to what's coming next.

It's likely that these new developments will be explored in Kingdom Hearts 4 or maybe even in Kingdom Hearts 3 DLC. For those that have completed Kingdom Hearts 3, read on to learn possible plot points for Kingdom Hearts 4, but everyone else should be weary of major spoilers for the latest game in the long-running series.

4 1. What's in the Black Box?

Kingdom Hearts 3 has a lot of unanswered questions, and one of the most frustrating for fans is undoubtedly the question of what is in the black box. Throughout Kingdom Hearts 3, Maleficent and Pete follow Sora and the gang from one Disney world to the next in search of the black box but can never find the right one. Then at the very end of the game, Organization XIII member Xigbar (also known as Luxu) is seen with the black box, though we never get to see what's inside.

Maleficent believes the black box contains the Book of Prophecies, a powerful relic in Kingdom Hearts lore, but we don't get confirmation that she's right. All we know for certain is that the black box contains something important, and hopefully Kingdom Hearts 4 will finally let fans see what's inside.

3 2. Xigbar and the Lost Masters

kingdom hearts 4 theories what the next game will be about

Speaking of Xigbar, it definitely seems as though he is being positioned to be one of the franchise's new big bads after the events of Kingdom Hearts 3. Now that Xehanort and Organization XIII have finally been defeated, Xigbar and the Foretellers (also known as the Lost Masters) may take their place as antagonists in future sequels. They may also be joined by their mysterious leader, the Master of Masters, whose identity still has yet to be revealed.

2 3. The World Ends With You

If players manage to find all of the Lucky Emblems in Kingdom Hearts 3, they will be treated to a secret ending that perhaps offers the biggest clues as to what the future of the series has in store. In the Kingdom Hearts 3 secret ending, Sora is seen in Shibuya, Tokyo, which just so happens to be the setting of the hit Square Enix handheld RPG The World Ends With You.

With The World Ends With You's setting being featured so prominently in the Kingdom Hearts 3 secret ending, one has to imagine that the game world will play a significant role in Kingdom Hearts 4. One theory is that Sora died at the end of Kingdom Hearts 3 to bring Kairi back, and will be participating in TWEWY's "Reapers' Game," that would allow him to return to the land of the living if he succeeds.

1 4. Final Fantasy Versus 13/Verum Rex

kingdom hearts 4 theories what the next game will be about

In Kingdom Hearts 3, players encounter a game-within-a-game called Verum Rex, which stars a stereotypical spiky-haired Square Enix protagonist named Yozora. Verum Rex appears to be a nod to Kingdom Hearts 3 game director Tetsuya Nomura's Final Fantasy Versus 13 project, which never really materialized and ended up becoming Final Fantasy 15, so some thought the Verum Rex segment was just a clever meta reference to some of Nomura's past work.

However, in the Kingdom Hearts 3 secret ending, Riku appears in what appears to be the world of Verum Rex (some believe Riku is in Shibuya with Sora, and others think he may even be in Final Fantasy 15's Insomnia), as he is being observed by Yozora. This indicates that Yozora isn't just a fictional video game character, but actually exists in the world of Kingdom Hearts. It could also be a indication that Kingdom Hearts 4 may very well explore some more original Square Enix worlds besides just TWEWY's Shibuya, so perhaps the next game will address complaints about Kingdom Hearts 3's lack of Final Fantasy characters.

Kingdom Hearts 3 is out now for PS4 and Xbox One.