Final Fantasy 7 Rebirth features characters continuing their fight against Fate and struggling to live in the new timeline that's diverging from the timeline of the original FF7. Square Enix is changing the rules of remakes, with FF7 Remake making drastic changes to the story of FF7. However, even if a character survives past the point of their death in the original FF7, it doesn't mean they're safe.
[Warning: This article contains spoilers for FF7 and FF7 Remake.]
Final Fantasy 7 Remake revisits the story of Cloud and his party, but this time the story has more depth and makes several changes from the original. Final Fantasy 7 Rebirth will continue the story where it left off, and there will likely be more attempts from the Whispers to kill the characters who have managed to escape death in the first part. The addition of the Whispers to the FF7 universe means that main and supporting characters alike have another obstacle to face as they work to save the planet.
The newly added Whispers work to keep the timeline on the path of the original, which lends FF7 Remake the feeling of a Final Destination film when they attempt to kill characters who have managed to survive longer than intended. Biggs and Wedge in FF7 Rebirth face this problem because they have survived past the fall of the Sector 7 plate, the point at which they died in FF7. Now, the Whispers are targeting them in order to fix the timeline.
Whispers In FF7 Remake Are The Equivalent Of Death In Final Destination
In Final Destination, characters who manage to defy Death are hunted by Death itself in order to correct the balance of life and death since they are no longer meant to be alive. While the Whispers also attempt to kill those who have survived longer than they are supposed to, they go beyond that and try to correct any changes to the timeline, even if those changes aren't related to death. This is why Whispers attack Aerith in FF7 Remake, as she seems to know about the original timeline and can therefore change it. Aerith even mentions that it feels like the Whispers take something from her every time they touch her, which likely means that they're trying to get rid of the knowledge she has of the timeline to prevent her from being able to change the course of Fate.
Unintentional or not, FF7 Rebirth is going to have a Final Destination vibe to it. As changes continue to occur, the Whispers will seek to negate the effects of those changes, such as when they forced Wedge out of the Shinra Building to kill him after he survived the point at which he died in FF7. This Final Destination style is one of many new obstacles that the cast of FF7 now have to overcome in Final Fantasy 7 Rebirth.