How will the world end?

It will have to be something more powerful that man if the entire earth is destroyed. So I am with you on the asteroid theory

Pandemic creation

disease and famine.

It will be burned up with fervent heat

With a big bang.

We get swallowed by a black hole.

all the worlds nuclear rectors will melt down and everyone will die from radiation poisoning all that will be left are cockroaches

With God's wrath.