There has been a lot of stuff in this thread, so I think it might be useful to recap all we know for sure so far:
- The biggest new thing in the remake are the Whispers. They are described as "arbiters of fate" (Barret), "voices of the planet (...) those born into this world. Who live and who died. Who returned. They're howling in pain" (Aerith), and as "entities from a future timeline that fight to protect that future that gave shape to them" (Bestiary);
- They intercede whenever events threaten to deviate from the OG. It doesn't matter who causes the deviation (Cloud when he almost kills Reno, Hojo when he almost tells Cloud about his past, Sephiroth when he kills Barret and so on). However, Aerith clearly states that they are howling in pain because of Sephiroth;
- Near the end of the game, a massive amount of Whispers comes together and forms the portal through which the party goes through. They arrive at an alternate version of Midgar. Things that happen there don't impact the "actual" Midgar (the whole city is destroyed in "alternate Midgar", but remains intact in the "actual one");
- Events happening within "alternate Midgar" are visible to people outside of it in multiple points in time (Zack sees what is going on from a distance, even though he is in the past). Thus, "alternate Midgar" might be a "singularity;"
- Inside "alternate Midgar", the party fights a massive monster created form an agglomeration of Whispers, as well as three smaller ones. The smaller ones fight with "a sword", a "bare hands", and "guns;"
- During the fight, they see a number of visions of events that happened in the OG but at a future point in relation to the remake (Meteorfall, Red XIII running through a deserted landscape, the moments before Aerith's death) and so on. They interpret those events negatively (saying things like “this can’t be our future,” “this would be the result of us failing today”).
- The party defeats the Whispers. However, what happens to the Whispers is unclear. We latter see Sephiroth controlling them (which he hadn’t done until then). This, in conjunction with the cutscene that plays right after the Whisper fight, have led some to interpret as Sephiroth having absorbed Whispers.
- Even after the party defeated the Whispers, Sephiroth still invites Cloud to join him in “defying fate”. Cloud refuses. In what is possibly the most cryptic scene so far, Sephiroth talks about the “edge of creation” and declares that Cloud has “7 seconds until the end”;
- After the talk with Sephiroth, the party finds themselves outside of “actual Midgar” (which remains undestroyed) and leave to pursue Sephiroth.
Now, I’m not quite sure how to interpret this, but I’ll give it a try.
It seems to me that the three Whispers at the end (who fight with a sword, bare hands and guns) might be Cloud, Tifa and Barret from a future timeline. Like the other Whispers, they have already “died and returned”. Going from the visions the party had, they come from a future where a sequence of events like that of the OG has already happened. Aerith and Red XIII might not be among the Whispers because their future selves are respectively in the Lifestream and alive.
Sephiroth is acting to stop the chain of events that the Whispers are trying to maintain. This implies that he has somehow acquired knowledge that the actions of the Whispers are against his best interests. The party, however, sees only specific glimpses of the future – all of which, lacking context, look terrible (a meteor falling, Midgar abandoned, Aerith about to die). Thus, they misinterpret this future as bad, and act against fate (as Aerith put it, “the future is always a blank page”).
I think that, in the end, Sephiroth got what he wanted from that confrontation. The party defeated the Whispers, and Sephy is later seen (possibly) absorbing and (definitively) controlling them. I don’t think he was thwarted at all, since he appeared to be in control the entire time. But I’m not sure that Sephy got all he needs. Otherwise, it wouldn’t make sense for him to ask Cloud for help in defying destiny. In other words, taming the Whispers might be a necessary, but still insufficient, condition in achieving his plans.
Now, I have no clue where the devs are going with this, and whether it implies that they won’t follow the OG anymore. We’ll probably just have to wait for an interview to shed light on that. I also have no idea what the deal with the “7 seconds” thing was.