One of the most important things about making a game franchise a success is figuring out the formula. Even if the franchise sees a lot of settings and unique storylines, the traditions and core structure of the games are what'll make players keep coming back. Once that structure is nailed down, the developers can add new things and look for chances to be creative. Persona is one franchise that's nailed that down. While the core structure of vigilante teenagers wielding supernatural forces remains the same, the approach is always different, whether it's Persona 4's TV-centric Midnight Channel or Persona 5's sprawling Palaces in Mementos.
Now that Persona 5 and Persona 5 Royal have made their mark, fans can look ahead and start thinking about where the Persona franchise will go next. Persona 6 is in a unique position because of how many fans got into the series thanks to Persona 5. Atlus has some liberty to experiment with Persona now that it's proven its mastery of the formula with the latest games. Unique side games like the Persona dancing game spinoffs and Persona 5 Scramble: The Phantom Strikers indicate that Atlus is happy to look at very different styles of games while still working with Persona traditions. Here's a few games that might be good sources of inspiration for Persona 6.
Fire Emblem
One of the best possible sources of inspiration is actually an acquaintance of Persona. In 2015 there was a crossover between Shin Megami Tensei, the older sister to Persona, and Fire Emblem. The core gameplay of Fire Emblem might play very differently from Persona, considering it's a tactical RPG, but the social elements are very similar to Persona's Social Link and Confidant systems. Via the Support system, Fire Emblem players can get to know their allies and are rewarded for it. However, it isn't just the bonds between player and NPC that matter. Fire Emblem: Three Houses lets NPCs become better friends with one another by being better friends with the player.
That's something Persona 6 would be wise to look into. The franchise puts a heavy emphasis on the protagonist building bonds with Confidants and becoming stronger for it. Adding interactions between the NPCs would make the Confidant system more impactful than ever. For instance, Persona 5 Royal introduced Showtimes, very powerful team attacks between two of the Phantom Thieves. In Persona 6, Confidants could unlock unique but limited strategic abilities thanks to friendships between two characters. These bonds could also be a gateway for special passive abilities when two friendly teammates work together or get the protagonist unique items.
Animal Crossing
Fire Emblem might have a fair bit of common ground with Persona, but Animal Crossing is much farther away from the core of the series. Still, Animal Crossing has some traits that could be worth taking for Persona 6. Even though there aren't battles staked on the strength of one's bonds in this social simulation series, friendships still matter a lot for the mayors of Animal Crossing villages. The player has to do tasks to help out the villagers to develop a community.
The Persona Confidant or Social Link system might benefit from these tasks. Confidants are mostly developed by visiting a character enough times to meet thresholds for cutscenes, and sometimes require a side quest to be completed. By introducing more interactive elements to Confidant interactions, like searching for something or going out to investigate a plot thread by hand rather than by dialogue, the Confidant system could grow.
Customization and creativity is also important to Nintendo's franchise. Animal Crossing: New Horizons allows players unprecedented levels of control over decorating their private island. Persona games could take a hint from that too. In Persona 5, players can fill Joker's bedroom with memorabilia from Confidants and useful furnishings like a TV. However, it's hard to know how to get all these decorations, and they all have assigned locations in the room. Persona 6 would really stand out if players had much more freedom to add personal flair to the protagonist's outfit and their living space.
The Elder Scrolls
Bethesda's Elder Scrolls franchise is another RPG in a very different style from Persona. Although both franchise encourage players to explore the setting and constantly interact with its rich characters, Persona isn't nearly as open world as an Elder Scrolls game. The ability to control one's experience would be really meaningful in Persona 6, though, specifically in the form of the protagonist. Elder Scrolls games, especially recent entries, have pretty strong character creators. Players would love to play a custom protagonist in a Persona game if Atlus were willing to write a narrative that makes it work.
Players would also benefit from more liberty in how they interact with NPCs. Part of the beauty of a game like Skyrim is that players can explore the world at their own pace and meet the majority of the characters as soon as they like. While Persona 6 will probably still be very story driven, it would be great if more Confidants weren't locked behind plot points. Characters like Haru Okumura sometimes suffer in Persona games because they take so long to become part of the story that players can't get to know them easily. Persona 5 might have been a very different game if Haru could be met as a Confidant early on, only for her true role to be revealed halfway through the game.
Persona Will Change
Persona 6's form will come down to what Atlus wants to do with the franchise's vastly increased fame. It could be that the developers decide to stick with tradition and give fans more of what they know they like instead of doing anything drastic. However, games in a series can't just repeat themselves. It'd be best if Atlus finds ways to expand on tradition. After all, that's why expanded editions of the games like Persona 4 Golden and Persona 5 Royal do so well even after their predecessors. They operate on the same principle as a sequel: Atlus takes what works and finds ways to build on it. Lots of games are doing things that could be adapted for a Persona game that's very unique. Another entry in the series might be a long way away, so fans have lots of time to hypothesize.
Persona 6 is rumored to be in development.