I'm guessing (hoping) we don't see an S8 until July of 2016. I would expect we'd see something like 8TH/s @ 1250 watts.
i'm expecting 10 TH/S for 1000 watts
maybe around nov this year after halving I still think we're a year off before we reach effective 1TH/100w - at least on 110V miners. 240V rigs will be closer to that goal.