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[Naqaj]

There was no controllable player movement during the battles in XIII, I don't grasp your distinction between engine & combat interface.

Xzen was talking about the game engine of XIII Versus. Some gameplay videos on youtube show it has a very dynamic, action-heavy combat. As XIV uses the same game engine, the same kind of combat should be technically possible in XIV.
ATB gauge, Stamina bar and stacking commands are elements of the combat interface, not of the game engine itself.