If I do a TBolt thru Best Buy retail, I could sell it back for 50% in 6 months, at which time I'm due for my last NE2 upgrade. But if you go with that plan you'd get a new phone every 6 months for the price of 1 retail annually. There is, of course, absolutely no guarantee that you can just activate a new phone whenever and keep the same data plan.
The other question is whether you can keep unlimited LTE on a contract upgrade. I say that's unlikely, and it may not matter regardless. At best, even if they only throttle you then what's unlimited LTE really worth if you get 3G speeds after just 2gigs of data?
Maybe the rooted tethers aren't enough of a problem/issue for VZW to bother with. However, I find it hard to believe they will continue to practice that with LTE. Although I would think throttling would be sufficient.