Source: imgur.com
One of the biggest challenges with making any sort of prediction with circumstances beyond our control is that we can be terribly wrong. Krugman can join the ranks of many others who have been very wrong about the predictions that they have made.
What can we learn from this? While it is very important to be optimistic and speculate realisticly on just how far technology can take us it is equally important to control the variables that you can and in the words of Mahatma Gandhi:
The following links include several list of terribly wrong predictions about technology:
Top 10 Bad Tech Predictions
Top 30 Failed Technology Predictions
Use It Better: The Worst Tech Predictions of All Time
26 Shockingly Bad Predictions