David Pogue has decided there is no point extrapolating future trends from present technology. His examples project progress to the point of ludicrousness: "Palmtops can't get much smaller without having smaller screens. ... How big would screens be by 2010 -- one inch diagonal?" So, it's largely an exercise in stating the obvious: immediate trends can continue, but they all have limits.
However, he's not entirely right in assuming "breakthroughs of the future will rely on technologies still in their infancy." For example, a few years ago one might have thought no current keyboard technology would allow millions of people to happily type many electronic messages, short of fumbling at miniscule QWERTY keyboards. And yet right now people have learnt to type messages very quickly on a 12-key cellphone keypad -- no new technology was required but a social and cultural need encouraged us to learn new skills to overcome current technology's limitations.