I agree. The development of a nation wide, let alone North American wide network would take billions more in development, planning, execution and maitenance.
On top of that FCC is the US, remember getting rights to put up towers here in Canada, and the rest of the world would be a little more difficult. This editors opinion of a Do it all phone would be neat, provided you stayed in the US, once you leave.. well you leave the network. Unless the phone had a GSM technology for say roaming it would be utterly useless to the corporate world.
The other issue will be security.. allowing such 3rd party and open development and freedom in a telecommunications industy can cause a few problems. Nothing horrible its just possible. But go everywhere VOIP cell phones, deffinately a cool idea, no more Hot Spot hopping if you will.
Overall the idea, a good one. And not impossible, just i wouldn't see it coming anytime soon. It would take alot of money and time and the rest of the world would be able to see them doing it so Corporations will have plenty of time to react accordingly.
But only time will tell, definately a cool vision though.