It would certainly be nice to have for the fighting games I play. A few have toyed with the idea of “shadow fighters”, but it never really feels like playing against a person. It might get their habits down, but it doesn’t replicate the adaptation of facing a person and having them change how they play based on how you’re playing. If someone could crack that nut, everyone would have someone on their level to play against at any hour of the day, no matter how obscure the game is.