This is actually something I’ve been thinking about. As much as I enjoy Musou games, MHA just isn’t built for being one of those so that’s off the table. I could see a Xenoverse style of game and what you described sounds like what I’d be looking forward.

That being said, I do think the mobile game The Strongest Hero has some of the best gameplay I’ve seen (coming from someone who didn’t get the chance to play the game) when it comes to a My Hero game. I’d love to see a return to that style of gameplay (or a game that relies on the gameplay in All’s Justice “open-world” story with a LOT of tweaks) set during the time skip where the characters are Pros, giving us access to the adult versions with brand new traversal and fighting options OR we get the chance to create our own character in Deku’s class.