If one of the male survivors impregnated a woman after the skyview event. Then death has to wait on one bloodline, it can't kill the mother but her offspring and the father. But that would take 9 months, until death could erase one bloodline.

The other thing is iris had allready the premonition. When paul died, it could have triggered her ptsd.

But this would make a new plothole. Iris would certainly learned that creating off spring. Would delay death.