This doesn’t apply to a specific franchise, but I sometimes think about how fun it would be for game franchises with a lot of characters to have games designed around replaying them with the different characters. Some examples would be:

A game with every Final Fantasy character that plays like Vampire Survivors. Each character would have their own sets of equipment and attacks they can obtain.

A game that is basically Sonic and the Black Knight be re-imagined to be more like either Monster Hunter or Kingdom Hearts. Each character could either have their own sets of equipment or have access to most of the equipment but use them differently.

A Touhou game that’s some form of an RPG, whether it be turn-based, action, or something similar to FF12. I know that there already are some RPGs featuring these characters but (on top of mostly being adult games for some reason) they all only have a few of the characters and they are very short and the RPG elements are usually quite limited.

Also, not really a specific franchise and it’s technically the same genre but I’d like to see more fighting games play like Dissidia Final Fantasy. I want to play more fighting games but Dissidia is the one of the only fighting games that I’ve ever been good at.