I'm all for an apocalypse but yeah, humanity is not going extinct any time soon.
Technology is too advanced for that.
As I keep trying to explain, we could easily survive on mars right now if we could get there fairly easy. It's going to take alot to make this planet less hospitable then mars, and even then, we could still survive.
Why?
It's simple, the harsher the living conditions, the more of the population will die, which means less will be needed for the humans that remain. Even without many (or any at this point) fossil fuels etc, small groups of humans could survive, even without any atmosphere at all. It would take something huge to actually wipe out all humans on this planet (A large enough meteor to smash the earth into multiple pieces for instance).
We may not make it into space until most of the humans living on the world die, and those remaining rebuild, but we will probably eventually colonize other worlds/moons in our solar system at least.
I wish I believed we would do that without destroying this planet, to the point where humans are pretty much all that is left (other then those animals raised for consumption or as pets). Sadly I think us destroying nature to such an extent (probably while in the process of destroying most of our population) is very likely.
We are like locusts apon the earth at this point, with the only primary difference being, we are intelligent locusts that will be able to survive after we eat everything in our way.