I was looking at the Boost mobile website a couple weeks ago(not switching, looking for a friend of mine down in Tennessee) and seen that they already have 2 phones out that have LTE capabilities, the phones are the HTC One SV(299.99) and the Boost Force(199.99). Not to bad pricing on the phones, if someone can afford them.
http://www.boostmobile.com/shop/phones/#/