They should switch asap. LTE will be way more common which means way more phones/support. Nobody's gonna wanna make phones for WiMax when it'll only cover 1/4 of the market as opposed to the 3/4 which will run on LTE.
well i guess till they see a downfall they will.. because from what i remember LTE is actualy based of WiMax and Wimax is based off 4g.... so maybe the phones won;t actually be hard to make.. and plus the reason why sprint went with Wimax so they can have control of their network and not have to listen to whatever company owns it...