A few years back I realized that iPod hard disks would likely outgrow people’s music collections, removing a big driver of people trading up to larger iPods.  I figured that Apple would have to find some way to use up more disk space in order to keep driving upgrades.  Video fills hard disks, but as John Gruber points out, it also makes people eager for larger screen sizes and better battery life.  Apple has at least a few more years of heavy upgrade business ahead of them.

Daring Fireball: Showtime: The New iPods
In the same way that storage capacities have grown over time, so too will screen sizes. And when larger-screened video-playing iPods do ship in 2007 or 2008, it doesn’t prove fools who reported that they were going to ship last year or this year right.