I am not sure how to reconcile my general agreement with what you are saying with my real life observation of how rarely I see people with Apple hardware older than 2, maybe 3, years old.
To put it in perspective, though, most of Apple's customers only started buying their hardware in the last two years and rarely purchased older models.
Do you have any references for that? That sounds rather weird since I know in university back in 2006/2007 probably about 90% of the student population had macs. Coffee shops have similarly been dominated by them for at least 5 years now.