I think another possible explaination is what we're seeing in the smartphone vs PDA market. Recent sales data suggests that PDA sales are relatively flat while smartphones are increasing in popularity. Why?
PDAs that lack wireless connectivity are information islands. Wireless network connectivity is the future.
Reed's Law (the assertion of David P. Reed that the utility of large networks, particularly social networks, can scale exponentially with the size of the network) and
Metcalfe's Law (Metcalfe's law explains many of the network effects of communication technologies and networks such as the Internet and World Wide Web) are theories that support this assertion. We are social creatures after all, and how we use technology on a network to communicate and interact will determine the type of devices we will use in the future as wireless connectivity become ubiquitous. Reed's and Metcalfe's Laws will dictate the growth and ubiquity of mobile connectivity. PDAs and other portable information and entertainment devices that lack wireless connectivity are destined for extinction.
For an interesting read on the subject, check out
Smart Mobs: The Next Social Revolution by Howard Rheingold.