Hell, I live in NYC and Sprint isn't even going to offer it here! If it's not in NYC, there's a slim chance it will reach some no name cities.
Secondly, the costs! Data plan's aren't cheap, experimental plans aren't cheap, and Sprint isn't cheap, so I don't expect an experimental data plan from Sprint to be cheap. Then again, that's just me.
Thirdly, the battery.
So, on another note I just got a N810. I don't want to wait for the wimax version, and I don't even know if I will use the wimax or be impressed by it. I am selling my N800 on ebay, so I will do that shortly and post again in the for sale section.