ATB or a turn-based system like Tactics/X would be wonderful. XV was an action system for a variety of reasons and it was totally understandable from SE's standpoint, but I hope that was something specific for that game and not the start of a new direction for the series. There's just too many action RPGs out there and ATB was so iconic of the FF series. However, FFXV was a big success for them and they are also not blind to the successes of Witcher/Dragon Age/Dark Souls so it would take a huge faith in their developers and fanbase to go back to turn-based. SE is such a big company with a big focus on the bottom line that they may not take the 'risk' by switching FF back to turn based.