We have God’s promise that He will not again inundate the earth with water. After the flood there were just eight people. Life went on for those eight.
Presumably He will use fire.
Or disease, or a vaccine created by Godless men that goes wrong, or air, or earthquakes, or famine, or the climate goes wrong and we enter a new ice age, or Islam or China rises and oppresses the west for 500 years turning us into commie slaves, or we are invaded by aliens.
If you are dead what does it matter what killed you?
If you are alive, what does it matter what killed 99% of humans?
All a bit academic HOW it happens. Who cares? Nobody is standing there thinking, "I am sure happy that God did not use water again. What a blessing!"
How long do these prophecies get to be validated? If in the year 2875 there is a fiery meteor that destroys Luxembourg and Belgium is Akita true?
If the Sun has a CME burst in 2145 and the electronics are all fried and people starve in large numbers, does that count? Is that fire falling from the sky or the grid failing and people dying from the collapse of a complex economic chain?
Given a long enough wait, almost any prophecy sufficiently vague can be fulfilled. For the "seer" it is a one way bet if they don't make statements that are too specific or have a timeline attached.