Square really needs to be extremely specific when they let these kind of details loose.
This.
This isn't something you just casually drop and hope no one will notice. It's raised a ton of questions. It's natural for people to get cheesed off at this, since it isn't what we were expecting in the slightest, based on the two trailers and info they'd shown so far. This came out of nowhere.
Whilst it could be for good intentions, such as getting the first part out of the door earlier, and prioritising each part as they go, this has me slightly concerned about linearity. It really depends how big the "parts" are, but if it's episodic, surely the focus would be on streamlining things a bit to focus on story. Would we still have that freedom to explore the world map or drive/fly around the world to visit any town when we want? Maybe things open up in "part 3," whereas previous ones will be more linear.
Can only speculate until we get more concrete info, but the handling of this pretty important detail isn't very clever. I hope it's for the good of the game, but it makes me wonder about how we go about purchasing a full physical copy on day one, collector's editions, etc. I guess the idea is that these actually will be entirely separate disc releases, so they would have to be pretty big parts to do that. See? Too many questions. Hope this is cleared up very soon.