Greetings all... As a longtime GSM user who has migrated to Verizon's LTE system, there's another issue on WiMax devices that preclude them from ever being converted to work on LTE. USIM cards, or in the case of Verizon and Sprint, CSIM's (USIM's that work on CDMA). With no CSIM support, there is no way WiMax devices could work on LTE and no way they could use eHRPD for that matter.
Hope this helps.