Aerith could survive, but if that doesn't come at some other great cost, the narrative tension suffers significantly. At the moment I think they're trying to keep the fandom guessing of whether it will happen or not. Since killing her didn't work last time, Sephiroth may have a new plan.
I have an opinion on this.
Zack and Aerith being alive is just boring. Kill them Nomura, it's more fun that way
That's why I hate AU stuff, it makes everything kinda meaningless. JUST KILL THEM
I don't think FF7-R is even close to subtle in what it is, whats going on or in its intents going forward. I also don't think the creators have quite the same relationship with the story as you, or many fans.
Personally, I'm just happy to step back into this world and enjoy the ride either way.
Anyway, this isn't a remake in the strictest sense, its a sequel and remake in one. It's clearly tied into the novels, where Aerith is figuring out a way to stop Sephiroph who has become a cancer in the lifestream & the horror-show that's happening to humanity. Neither are happy and want to change the ending and this is the result of that.
As to what to expect. Well, they have said they will keep the main story beats in-tact but there will be changes. If we take it at face value and pay attention to what part 1 is showing us, it's quite clear what they intend to change and why. The entire destiny thing is hammering, with the subtlety of a baseball bat, screaming "look, we're doing this thing", that the protagonists plan is to change Aeriths fate (her to live) and to change the ending from the bad ending of the original (and compilation works) to a happy ending that prevents all the bad stuff happening in the compilation.
Nothings going to change that, they've committed to what they intend to do, and diverting away from that makes no sense at this point. Why on Earth would they put in all that extra stuff with destiny, with an explicit focus on two specific things, only to go ahead and do those things anyway? They might as well just do the 1:1 remake.
I think people just need to come to terms with this now. While it's possible, it's extremely unlikely she will die in this. I do think there will be a trade-off though.
If it's any comfort, I have a suspicion, given where her death originally took place, that we will have multiple ending scenarios with at least two paths. I wouldn't be surprised if the OG path is one of them, and a path that leads to a happy ending with the catch being that it'll be a much harder route to take. That's what I think we will get, with some minor changes and some stuff with Zack along the way. In regards to what Clement Rage posted, yeah, I think the trade-off is going to be related to what Sephiroph has planned and will probably spin out into a harder path overall, with some other consequences. Probably the whole "changing who we are" being a bit foreshadowing.