well that is 1060 performance per card right there??!
why bother releasing a mining card if not significantly faster eh?
Lower cost and higher efficiency.
I expect a "mining" GTX 1060 varient to use 20-30% less power than a non-mining varient at the same clocks, due to no video circuitry + disabling all of the non-mining-related parts of the GPU itself in the BIOS.
Same reason a R9 290 with a BIOS from TheStilt runs a LOT cooler and lower power usage even if you DON'T use one of the undervolt varients, only more so.
It also is apparently going to carry a MSRP about $50 lower, probably due largely to the removal of a lot of circuitry - but the postings from retailers I've seen claiming to have the card have all listed it as a somewhat inflated price.
They need to get it under $200 to make it interesting.
It should also run cooler at the same clocks.
I suspect they will also change the BIOS to tighten up the memory timings somewhat (something else those TheStilt BIOS did) to increase hashrage, but the folks claiming 60 Mh/s out of the rumored 1080 varient are full of .... something. That GDDR 5x latency is STILL going to kill hashrate, they'll be lucky to get to 45 and I'd expect 35-40 at best.