The world is never gonna end, we're just going to be extinct.
I'd say radioactive super ants would be pretty cool.
It will end eventually. It will cease being able to host life when our sun goes red giant in 5 billion years, and potentially get completely obliterated when that happens anyways. At the very least Earth's atmosphere will burn away and the oceans will boil away leaving it a lifeless barren rock.
Zombies, because that's all the rage right now. Alien Aliens. Alien invasion.