I think Max noticed that every time Aerith talked, there was this white feather, so it might be her. However, it's not exactly true; it appears at first in the trailer, then again but the scene *is the same* and we see it when Cloud talks, too. So I don't think it represents Aerith. It may be a reference to Genesis, or maybe because Cloud's about to die in this universe.
I'll notice that her speech "let's not talk about the past (images of Zack and Cloud walking near Midgar) but the future (images of Meteor)" certainly breaks it to people that Meteor is still the future of the Planet right now (I think it was Max again saying that it was now in the past, but I disagree vehemently lol).
What also bugs me is that the whole part of Zack and Cloud at the end happens *after* the "what facts are only fiction?" - while it certainly alludes to Cloud's personality trouble, does it ALSO alludes to the whole part of Zack being alive? IS HE A DREAM? Cue in Cloud wondering where Zack is??? I am almost certain now that this line is from a dream he has. Maybe we spend the night in Gongaga and he dreams about Zack, IDK? Or maybe that replaces the dialogues he has with himself in Junon about Tifa? I think it's probably something *added* rather than replacing, because they are going to confuse the hell out of us. Things are going to amp up even before we reach the Temple of the Ancients - Tifa wondering if he's really him, Aerith searching for him, Zack dream, they'll want to confuse people even more than in the OG. Shit's going to get real.
The breaking down of the narrative is super interesting in the trailer BTW:
- Tifa asks him if he believes she's not the same from before, images of the Kalm flashback, but line most probably from the Northern Crater
- Aerith praying, Holy in the water
- "What facts are only fiction?"
- back to the images of Zack and Cloud near Midgar that were from the beginning of the trailer (THE PAST)
- Cloud: "I don't understand. 5 years ago, did we come here together? Zack... where is he now?" > talks to Zack
- Aerith: "It's you... I want to see" > talks to Cloud (GS date, alluding to his personality trouble)
- Zack: "Sorry. I don't know how to help you." > probably talks to Cloud (most probably heartbroken because Cloud is mako poisoned and he can't do a thing about it; maybe even because Cloud is dying)
BOTH Aerith and Zack allude to Cloud's mental problem, however they both do it after the "what facts are only fiction?" part. Tifa does it too, but her way of wording it is by asking if she's the problem (she isn't, her part is before that black screen; it's also funny because we know the Nibelheim incident didn't happen as Cloud says in the Kalm flashback, so it's sort of fake too). I really think it's a very clever trailer. It makes you believe at first that everything has changed but once you stop and look at it, we are exactly where we should be with the OG.
Re Zack being dead or alive: Aerith tells me that he is dead at the end of Remake, but that something is odd with him in Intermission. What she did at the end of the game certainly transformed his fate into something else, but she is not aware of this.