It won't outperform a GTX 1080 on Zcash - I'd guess more like 480-500 sol/s ballpark at optimal "full hash" settings.
A hair fewer cores than the 1080, and the memory system isn't a big factor to Equihash algorithm.
im optimistic, i see it doing 550-600 sol/s
Probability zero, 1080 cards don't manage that reliable if at all.
FEWER CORES = LOWER HASHRATE on Equihash, it will hash SLOWER than a 1080 though probably not by a lot since it's only a FEW less cores.
It also seems to be the same GPU, with one "compute unit" disabled, so it's very unlikely to overclock more than the 1080 to a measurable degree if at all.
Rated TDP seems to be the same as the 1080 cards, which makes sense since the GPU is so close. I could see it turning out to be 170-175 watt range instead though for "reference" level cards.
Equihash algo used for ZCash/ZEN/ZCL and suck is not nearly as memory limited as the algo used for ETH, or the 1080 would NOT outperform the 1070 by a fair bit and the 1080ti wouldn't blow both completely out of the water.
I talk about ETH and ZEC and their clones because that's where the money is - in terms of "total GPUs mining" ETH has more GPUs working then everything else combined, with ZEC in a solid second at a little less than half that (perhaps a third if enough ZEC miners are using NVidia cards) then a LONG drop to whatever is third at the time.