I think Sprint's kinda in a tough spot. They hooked people in with being first with WiMax semi 4G. Now they've said there going with LTE and they've partnered with Light Square for most likely some sort of high speed wireless.
So if your a customer with a WiMax phone your stuck and I doubt Sprints going to roll out any more WiMax service.
So when they finely decide what direction there going to go you'll have to buy another phone compatible with their new wireless high speed. And will that device be backwards compatible with WiMax. Are device manufactures going to be lining up to make odd ball phones just for Sprint...? Who knows.