That would be awful, simply awful. You don't want it to be like Final Fantasy where the battle system is significantly changed every installment. Small, gradual change, and not change for the sake of it. Like others said, persona is one of the last strongholds of turn-based battles and it should stay that way as it suits the game really well - these days, it sets SMT games apart as unique. That said, if ATLUS came up with an innovative system which seemed like a logical successor to turn-based combat I wouldn't hate them for it.