Here is a couple of interesting essays by Marshall Brain, the author of "How It Works"
Robotic Nation
http://marshallbrain.com/robotic-nation.htm (http://marshallbrain.com/robotic-nation.htm)
Robots in 2015
http://marshallbrain.com/robots-in-2015.htm (http://marshallbrain.com/robots-in-2015.htm)
He claims by 2050, 50 Million Jobs will be lost to robots.