You could add to your (self-answering) question "...would cannibalize their laptop sales..." the phrase: "...and that has perhaps 1/3 the profit margin?"
Apple's decision making looks to me more like (as with the MB Air), "can we develop a high-margin product that will draw NEW (ex-Windows) customers (and maybe some wowee press coverage)?"
Apple's decision making looks to me more like (as with the MB Air), "can we develop a high-margin product that will draw NEW (ex-Windows) customers (and maybe some wowee press coverage)?"