The impact hazard and the virus threat are very real.

It would be difficult to kill off 100% of humanity but what difference would it make if our civilization is destroyed and we have basically lost our foothold as the dominant species on the planet. If the whole world was like life in Afghanistan have we really survived?

He is right in the long run. However, there is no way to say that 1000 years is more accurate than 2000. I am optimistic that we will eventually expand off of this planet. I believe that it will be something less than 1000 years. It just won't be in the near future as some (including me) want to believe.

I also believe that we will develop the means to predict and counteract most potential impactors long before we have space colonies. If we are lucky enough to get a 10-20 meter impact in an uninhabited area it will happen sooner.