How long do we have?

Going to have to bring you down for a minute or two with a surprisingly bleak post. I'm raising the question "How long do humans have left." It's been playing on my mind a decent bit so I'm throwing it out to you loyal readers.

The way I see it, there's so many different ways that we are going to die it's ridiculous.
Gamma-ray bursts, Asteroids, black holes, super volcano, diseases, global warming, biotech disasters, Nanotechnology disasters, World War, Ai Taking Over, Aliens, divine intervention, ice ages, just to name a few.

It's quite depressing to think about but in my opinion we have very little time left. The rate we advance technology wise is unimaginable. We've moved so far in the space of 20 years its only a matter of time before we create something that destroys us.

Lets get some discussion going, in your opinion:
How long do humans have?
Whats going to take us out?