I can imagine a merger between the iPod and one of their computer lines.
A 13" Touch-screen computer that works with Wi-Fi, .Mac and Flash Storage. Take it home and dock it like an iPod in a simple elegant dock with a couple of USB ports and an optical drive. Therefore becoming a fully equiped 13" iMacPodTypeThing.
With Wi-Fi networks becoming widely available around the world, Increasing Web Applications, Wi-Max on the way, Cell Networks expanding, Google Storage, Apples Data Center and lots of other stuff. This is fairly close to possible within the next 2 years.