Though - if 1TH/s = ~$140 retail after chip, PSU, shipping, cables, and whatever else - and it consumes, say 500W (this assumes it's significantly more efficient than babyjet2s, which I don't think an unreasonable assumption. It'll probably be much more efficient than my grim guess) - 6-12 months out (6-8 months out might be okay), and it's hard to justify the cost even if electricity's dirt-cheap (say, $.05/KWh after taxes/fees) - especially if everyone else is going to be mass-ordering these chips, too. At the end of the day, we're all chasing a piece of a 3.6kBTC/day pie (+~100BTC in fees) until the next halving, which is probably significantly less than three years away with the rapid increase of hashpower put on the network. We may not even have much more than two years if upfront costs drop dramatically and the pre-order hysteria keeps up.
-So what do you see in, say, 18 months? Near-complete mining centralization in a small handful of geographic locations with sub-$.05/KWh electricity?
Well, based on assumptions like you just wrote you can calculate where its headed, just not how fast it will head there. Your guess is as good as mine.
But yes, I do expect the majority of mining (and all of profitable mining) to eventuallyt move where electricity is cheapest.
And there are some pretty extreme low (subsidized) prices to be found. In Kuwait the price is fixed at $0.01 per KhW:
http://www.bbc.co.uk/news/world-middle-east-20644964
In russia apparently you can buy electricity for $0.025 per KwH
Those tariffs cant last forever, as that is well below cost but even if its only for a few more years, its not unreasonable to assume someone will set up shop there and Kuwait would effectively subsidize bitcoin security