1) 4 billion years from now the Milky Way will collide with the Andromeda galaxy.
If that doesn't destroy the world...
2) in ~5 billion years the sun will begin to die, swelling up and possibly engulfing earth. At the very least, swelling up so big that life, as we know it, is no longer possible
if that doesn't destroy the world....
3) Dark Matter is causing the universe to expand at an ever increasing rate, carrying all the matter within it away from each other. The universe will reach an expansion speed that no longer allows for the formation of stellar nebulas, as gasses become spread too sparsely through out it. The absence of these stellar cradles marks the cessation of star creation forever. From here, a last star is birthed, destined for a lonely end. The remaining stars burn off their fuel then die, some exploding, some falling back in on itself to create black holes who also share the fate of death as they decay from Hawking Radiation. One by one, stars flicker, emit great amounts of energy, then fade into darkness with no hope for a new generation.
Eventually, the speed of the universe's expansion exceeds the speed of light, meaning all remaining stars will no longer be visible as their light particles are being pulled away faster than they can get to your eyes. Imagine being alive then, be it on a planet or in a habitable space station, to witness the night sky slowly lose its glow, to see the breath of the constellations slowly cease, to see the gods of the ancients die...
The idea of peering into the great infinity and finding...nothing, how would that affect the human psyche, to look up from your planet, or outward from a porthole in the space ship, and know that the sight of that once beautiful backdrop to our existence was an experience for the long-since-dead?
If you're alive long enough, you'd experience the drop in the universe's temperature as matter moves from low to high entropy, losing their energy and no longer having a way to produce more. Somehow, if you were able to pull away from the universe, in some god-like third person view, you'd find the universe descending into an impossibly vast, cold, dark, lifeless end.
Certainly that, above all else, will be the ultimate destroyer of worlds.