It depends on how much you mobility usage one wants to have in their lives. Unless there is a significant shift in culture, we're talking about competing with physical human interaction and experiencing life in the physical world. Everytime you focus on your mobile phone is less time you're paying attention in the real world.
For example, consider mp3 players. Good when you're alone, waiting for someone, on transit when you're not talking to anyone. People listen to more of as an activity to pass the time NOT as much when it comes to scheduling and purposefully listen to it.
If people becomes more isolated, somehow unable to interact as much with the real world, it'd say that mobiles will really take off in alot. I'm not denying that more laptops are being sold and that cellphone sales are picking up.
But having a tool and actually using it more and more is a different thing.
Lastly, troubles in the real world have a way of pulling you away from fancy gadgets and virtual activites. Poverty, increasing work hours, or even pressures of work like having to be on the phone (talking) constantly will decrease mobile usage.
But the biggest barrier is COST.
Yet, if we make it really easy & cheap or free to get good pdaphones and to post text, video, audio in microblogs, who knows?
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