[lukifer]

It definitely seemed like an arbitrary example; a better one would have been the move to the "fat" Nanos (which was a bold design shift, and not particularly well received), or the shift of the Nano brand into primarily the exercise+watch niches (including the removal of video, the signature feature of the previous iteration), or the redefinition of the iPod from music player to generalized pocket computer.

But the overall point stands; many other companies would have kept selling the successful iteration with only minor changes for as long as they could, and only made a bold shift when sales dropped or competition started nipping their heels.