I found the argument fascinating: he claimed that the dramatic growth of the computing industry was fueled by more people having access to computers. Beginning with mainframes, through to minicomputers, workstations and PCs, each wave was cheaper and was affordable to a much larger number of people. This increasingly larger audience is what fueled the growth. But such growth can't continue forever; eventually everyone has one. At that point, they still buy upgrades and replacements, but the dramatic rate of sales must drop back.
I think that's where the first world is today, and developing nations aren't that far behind. Of course, we'll still have new devices (iPhones, kindles, and others-yet-to-be-invented), but the computing industry as such won't grow at the unsustainably dramatic rates of previous decades.