Voice will still be the main function of most of these devices. Sure there are geeks who use it as an Internet device first, phone second (or third) but the majority of 'regular' people still need and rely heavily on the phone.
I liken this "phones will die" debate to the TV/Internet debate. People love their TV, they love being slowly fed this passive style of entertainment and no matter what cool stuff we invent for the web, there will (for the foreseeable future) always be a audience for one-way TV programming.
I liken this "phones will die" debate to the TV/Internet debate. People love their TV, they love being slowly fed this passive style of entertainment and no matter what cool stuff we invent for the web, there will (for the foreseeable future) always be a audience for one-way TV programming.