I doubt than anything will, unless it's the sun dying thing. We are in many ways, very much like a virus, and one of those ways is that we are damn hard to kill off. I suspect that within the century, war or economic collapse will destroy most of our civilization, throwing us back to the stone age. However, I find it likely that enough of us will survive to continue the race and eventually repopulate. Maybe, if that happens, we will learn not to kill the shit out of the environment and eachother, but i doubt it. vicious cycle anyone? If we ever manage to break the cycle long enough to populate other planets or even solar systems, than it would be almost impossible for our race to go extinct.