Overly Pessimistic?

Robert Gordon, an economist from Northwestern, questions whether our economic growth is over.  He does so from an interesting perspective: looking at the industrial revolutions.  Yes, that is the plural of revolution, as Gordon thinks we've had three.  The first, from 1750 to 1830, brought steam and the railroads.  The second, from 1870 to 1900, gave us electricity, the internal combustion engine, running water, indoor toilets, communications, entertainment, chemicals, petroleum. The third began in 1960 and produced computers, the web, mobile phones.

Gordon then moves on to estimate the productivity growth from these revolutions once the spin-off inventions had run their course.  He concludes that the productivity growth from the second revolution lasted from 1972 to 1996.  That from the third was much shorter, from 1996 to 2004.

Gordon's next point concerns the most powerful of the revolutions, the second.  Many of the original and spin-off inventions of this revolution could happen only once – urbanization, transportation speed, the freedom of females from the drudgery of carrying tons of water per year, and the role of central heating and air conditioning in achieving a year-round constant temperature.

His view of a future revolution is clouded by what he sees as very difficult obstacles:  demography, education, inequality, globalization, energy/environment, and the overhang of consumer and government debt. 

What do you think?  Is Gordon overly pessimistic?