So I was talking to someone about the subbed fourth trailer tonight, and it hit me.
What if the whole scene with Aeris and Cloud isn't a memory, but either a dream sent to him by the Planet, or Cloud somehow being brought before the Planet once more to be begged to for help?
Consider the movie Contact. In it, in order to make sure that the main character isn't shocked or surprised by the aliens and thus, too scared to receive their message accurately, they look through her mind and pull out an individual that she trusts, and use him / her to deliver the message for them (a go-between).
Imagine this same scenario with Cloud. At one point it's said that, "the planet is trying to fight us...". How does a planet fight back? Super plagues? Sure to get rid of the annoyance, but bound to kill anything else it comes in contact with. Cataclysmic upheavals and natural disasters? Too messy, no way to ensure that the targets they want dead will become dead. So...
Paraphrased from the conversation with said friend -
Planet / Lifestream Being: Fuck. We need to stop this whole Advent Children thing. Hey, wasn't there a guy, one of those early AC kids, that helped stop that big one before?
Other Planet Being: Oh yeah. Cloud or something.
PB: Yeaaaaah. Let's get in touch with him. He could help us.
OPB: Bring up that Aerith chick. He liked her, so maybe she'll be able to say, dood, shit is going down, do something about it. Kick it's ass again.
PB: Yeah, good idea. I'll get to it right away.
Or maybe I'm just an Aerith fanboy hoping that seeing Aerith again won't be some stupid flashback or something :/