I think what AI really challenges is the value of man. Our current world relies on the assumption that more people means more productivity/consumption, so more growth and stronger economy. With the potential emergence of more capable machines, this assumption may no longer hold.

How to deal with the left behind society? Trying to find them new purposes of life? How can we make sure those new purposes won't be automated in the future? Or if large portion of the population facing the problem of being jobless, is population growth/immigration still a positive thing? What about education? If we know that most of the people won't be needed in the workforce any way, is education still something worth having, except for very basic common sense?

This all leads me to think that the future might be more static and less energetic one, yet it might be more affluent than ever. It could also be more equal than ever, that most people might be under the care of some really intelligent system to spend their whole life, without really being required to achieve anything, but it will be OK, and will become the new norm. Population might decline, but they will be gradually replaced by robots, until new equilibrium has been reached.