All I know is from planning long ago, and that was that it was going to become more action oriented. But that in itself, doesn't really mean anything. I haven't seen the battle system (or what they have right now), so I genuinely don't know what that could be. I, personally, haven't been expecting a full action based system overhaul, and am expecting some kind of evolution or hybrid thing. That's been my impression anyway.
That's speculation based on something from long ago, so it's probably not worth much right now. Especially since I've seen first-hand how FFXV went through some changes in that aspect. I'll know soon enough since I'll get a chance to see what they've been doing. Pretty curious on actually seeing this game, rather than just plans and concepts or whatever. It's been a really long time.