Wireless carriers like AT&T and Verizon will not be able to continue the smartphone subsidy model that has driven widespread smartphone penetration to this point. AT&T CEO Randall Stephenson, speaking at an investor conference today, said the current model is not economically viable, reported CNET. With more than 75 percent of mobile phone users owning smartphones -- and that number growing towards 90 percent -- Stephenson said carriers will "move into maintenance mode" and that "the model has to change" because carriers "can't afford to subsidize devices like that". Many higher-end smartphone power users also tend to upgrade their phones as often as possible, something that can become expensive for carriers subsidizing those purch
