Less on a couple of my ETH systems - though not by a lot.
If AMD made a 754-based CPU on a semi-current process I could probably drop the 190ish watts my pair of 7870 single-card Semperon 3000+ systems and the 170ish the 7850/Semperon 3000 systam is using by 30+ watts each.
On the other hand - existing hardware, ZERO out of pocket for the most part (I did buy ONE HD 7870 locally for $80, but I figure it'll make THAT back by the time that system becomes unprofitable - and if it misses by a bit, no big deal it turns into a very cheap serious RC5-72 cruncher system).
Unless someone (Bitfury-based most likely) gets a 14/16nm custom-gen Bitmine miner out before the halfing, it's looking very iffy on my returning to Bitcoin mining at all this year - though I'm going to have to do some serious number crunching when the A4 shows up before I decide.
As much as I'd like to see a sub-$400 Bitcoin miner show up in that generation, I'm betting it doesn't happen this year IF at all. Takes about as much time and effort to design a small miner, the infrastructure costs on it are HIGHER per MH, making it that much harder to achieve ROI on it - and I suspect the market for such a "small" miner isn't all that big.
There's a REASON Bitmain has never bothered releasing a BM1385-based "U-series" miner design, much less an "R1" upgrade to the next-gen chip.