I completely agree with the author's argument about smartphones and tablets, but I think @nextparadigms is right about the MacBook Air. It belongs in a completely different market segment, along with $2,000 "ultraportables" from Lenovo and Toshiba. That segment has been there for a long time even before netbooks appeared.

It's definitely possible to pack a real Core 2 or i7 processor, an optical drive, and 10+ hours of battery life in a 11-13 inch form factor with a weight of no more than 3 pounds. It gets pretty damn expensive, though, even without the mandatory Apple mark-up.

Personally, I would urge anyone who has a good enough budget to get a real ultraportable instead of a half-assed Atom netbook. But if somebody is shopping for a $350 netbook, I don't think they'd consider the MacBook Air a serious alternative. If anything, smartphones and tablets are stealing market share from both netbooks and ultraportables.