The most likely rollout scenario for WiMAX seems to be for national companies to offer combined WiMAX/VoIP service.
A study based on a presentation made at the 2005 IOC Wireless Symposium by In-Stat's Eric Mantion gives WiMAX more than just a passing grade. In fact, the future is bright despite considerable sniping from the cellular camp.
WiMAX is likely to become an inexpensive way to deliver broadband in the U.S. As such, it could also be used for backhaul for cellular BTSs, which means, of course, that it could be an option for cellular phones.
According to Mantion, the most likely rollout scenario is for national companies to offer combined WiMAX/VoIP service. We'll have to wait and see how it turns out, however, because in technology there are always surprises.