Whatever softbank accomplished in Japan wont be very relevant to the US market, the economics and logistics of rolling out a LTE network across the united states is far more complex than japan. Japan has dense urban centers crammed into small places all over an island. The US has urban sprawl over huge areas, each tower deployed reaches far fewer customers and you have to construct backbone infrastructure (Surely LTE backbone requires fiber optics) which is expensive and complicated to run over long distances. Especially with the complicated and lengthy permit process to tear up city streets to bury cable. Verizon has already spent billions of dollars on their LTE network, money softbank doesnt have. They can maybe deploy LTE in dense metro areas, where fiber to the backbone is already close by, but not nearly on the scale of AT&T and Verizon.