Something that's already possible today: an ensemble for mobile computing instead of a monolithic device. You have a 4G wifi hotspot, a bluetooth headset, a tablet, etc. I'm curious how you could evolve that idea. Maybe with wearable computers, maybe something else.
My wife took my 3GS iphone last year when she lost her phone and for a few months I used a 3G iPad and a prepaid dumbphone we had lying around. It was a surprisingly decent setup. Because I do so much of my phoning on Skype the actual monthly charges were about half of what they were with my 3GS plan.
One thing I realized was the iPad plan is the dumb pipe plan we've all been waiting for. It's really a neat trojan horse Apple's set up with the carriers for some future disruption like an iphone nano where the bluetooth headset is the whole phone and they can sell the thing for $149 without a subsidy.
