Okay so, full disclaimer: I absolutely adore the Lifestream sequence, it's my favorite scene from the OG by far and I understand why people are bothered by this apparent call to shove so many scenes, themes and characters in what is a very private, intimate moment between Cloud and Tifa that is so unique in tone, depth and presentation. I remember after Remake people started saying that Zack could easily replace Tifa there because he knew what happened in Nibelheim and it really, really annoyed me because it completely misses the point. So I do get it, and I understand that there's a lot of bad faith either from shipping or from people who are uncomfortable with the idea that at the center of their cool videogame with swords and magic balls there's actually (gasp!) a very delicate love story.
However – and I mean no disrespect when I say this – this opposite belief that the Lifestream sequence, of all things, is going to be recreated basically untouched sounds a lot like me around Rebirh Gongaga, where I said out loud "well at least they got the whispers out of their system tho" mere seconds before a wild whisper appeared (true story)
I also don’t think that it should be a group project, but I want to play devil's advocate and say that I don't think that to include a reflection on Zack's and Aerith's death there is inherently a bad idea, especially in the context of the expanded Compilation. I think most of all Cloud has to process the fact that their deaths were not his fault, much like Tifa almost dying twice on him was not his fault (his original trauma manifesting time and time again). There is a thematic link there, there's setup for it imho in Remake and especially Rebirth, and it still all begins and ends with Tifa. Like all things, it comes down to execution and balance, for which I'm much less confident, but it's really not such an absurd idea from what they've presented so far.
It would also be weird even for them to create this entire Lifestream subplot (which revolves heavily around Zack and now Aerith) and then do absolutely nothing with it while, you know, we're in the Lifestream. I will go one step further: it's very possible that most of the bigger additions have been written in function of the Lifestream sequence itself. After all, if the Lifestream sequence is the emotional core of the OG, then it makes sense that it should be the emotional core of the Remake saga as well, if not of the Compilation as a whole; and that can't happen if the new elements and themes are not taken into account. To ignore them completely would actually lessen the impact of the scene at this point, and it's just not something I can see them doing, considering their... massimalistic approach, let's call it that.
If you ask me, the real threat to the future Lifestream sequence are not Zack and Aerith. It's their bad habit of having their cake and eating it too with wanting you to feel super bad for these characters but ALSO LOOK THEY'RE KINDA FINE BE HAPPY NOW, it's the camera that feels like it's on coke in a desperate attempt to remind you that this is in fact very dramatic, and big moment after big moment with no time to breathe and ten thousand boss battles back to back until you forget what you're actually supposed to feel.
The loudness worries me far more than Cloud and Tifa processing together the death of someone irreplaceable that they both feel like they have failed.