you are probably talking about S7 hypothetically, but I don't see it being a good large scale investment by summer, although with low electricity cost, who knows. I am pretty sure we will have at least 0.1-0.15J/Gh machines by then (S9?)
One thing is clear: unless speed of diff rises significantly decreases, buying btc directly would be more productive with zero overhang and maintenance cost.
Also, must consider a mass sell off of S7 come block halving. Who knows how cheap they will be. Those in low power cost areas may find the price attractive [Depending on what the price is]. Yes, we may very well see new gear at 0.1 to 0.15 J/GH by then. Yet, we may not. May not see new gear available to home miners until 4th quarter 2016. No one knows the price of bitcoin by then nor the difficulty. I have my thoughts of what they will be. I'm simply seeing how it plays out and make decisions as they arise while the block halving gets closer. I'm going to have at least 90 to 100 x S7's before block halving for sure. Then, based on difficulty, price of bitcoin, price of S7's and price of possible new gear; I will make my decision on what to do with present gear I have; the move; etc...
EDIT: Bottom line... It's all speculation...