The correct answer to this open question is the following.
One thousand years is a really long time for a civilization to last. The United States civilization is 244 years old.
I think we'll make it to 1,000 if we change the way we live and the way we treat each other. What would be considered our crowning achievements should be the respect and tolerance that as a society we can show for other ways of being, thinking, and act. Otherwise, we tend to auto-destruction or even extinction.
And it is not going to be due to climate change or global warming. It is not going t be for a great asteroid impacting the surface of planet earth. No.
It could be for the hate reflected in the destruction of other people and vice versa.
History clearly shows that entire civilizations disappeared for waging war. Others, for diseases. Just a few, due to massive extinction. Our civilization? Well, our biggest risk is that we disappear because we were not able to agree with each other understanding our differences, respecting them, and tolerating them.