Jobs have been made obsolete many times over. There are fewer blacksmiths than there used to be when a horse was a primary method of transportation. Manufacturing jobs declined during globalization/offshoring during the eighties. Did knowledge work take the place of those manufacturing jobs? Would the employment numbers look different if VisiCalc hadn't come along?

The questions are: what do the population numbers look like that are impacted by these changes in job-type demand? How many blacksmiths were many obsolete by the car? How many manufacturing jobs were removed from the pool by moving to offshore manufacturing? How many manufacturing/warehouse/etc. jobs will be replaced by automation?

The last question is probably the hardest to answer, because we don't know yet. It depends on the evolution of the sensors (solid state LIDAR), other hardware, and automation methods.