The LTE rollout is performed hand in hand with the Network Vision relaunch of our 3G network. It is currently on schedule to be completed netionwide by the end of 2013. A few areas have already been announced, but I don't remember which ones off the top of my head, the information was posted in a blog post here in the Community.
Here is some recent information on LTE rumored coverage:
so much for 2013 lol
its a safe bet i'll be getting a box of "well after 2013" lol
Just to be clear the SGSII Epic 4g Touch does NOT support LTE as stated on samsungs own product spec sheet here http://www.samsung.com/us/mobile/cell-phones/SPH-D710ZKASPR-specs
I'll give you the Sprint Cares response: "We are unable to provide any details until we reach that point."
Translation: They haven't figured out what they are going to do yet. Common wisdom suggests they'll do like they did with iDEN, push a deal to get any holdouts off of WiMax when they're ready to turn off all of the towers. In your particular market that may not happen in the 2 years you've got.
Probably something you won't need to worry about since that's one of the last WiMax phones they will sell. One would think Sprint will stop selling them at some point to make sure they avoid the situation you just mentioned.