Completely agree. Great Post! I would like to add in there the only other benefit of the 1070 in mining though is that is can do other coins faster (cuda based mining programs), like Zcash than radeons for now, I don't know if the radeons can catch up to this, cause I haven't tried to mine zcash yet, it might be something to do with the cuda algorithm. So once the Eth crazy goes which should be early next year when they shift over to POS, the 1070's have options to go to more coins.
Speaking of the best case for Nvidia which is Zcash
I've already experimented with this stuff, a lot. The 1070 needs basically to be unrestricted and wide open to get a hash rate of around 455. I mean you have to push it over 2100 core and over 4500 RAM and then it's sucking down 185 watts plus. If you dial it back reasonably to get into that magic 150 watt mark, after the tweaking and underclocking, you get a hash rate of around 390 which is actually quite good at 150W ... zero complaints. .385 watts per hash/s This is the best case for a 1070 imo. (per watt the 1080 is a bit better than this)
With the 480's I cut the vcore to .91 or .905 (less if stable ) drop the frequency to 1100-1150 on GPU and 2200-2250 on RAM and I get about 290-295 ish with an unmodded BIOS. modded BIOS and hacked drivers I get more. All this in about a 105-115watt envelope. .396watts per hash/s . This is the worst case for a 480 imo.
The above figures do not represent days of intensive scrutiny, that would be stupid. It was the best I could do on the bench over a couple days.
So it's a coin flip for Zcash and for everything else Nvida gets eaten alive in H/s per watt. There are no coins the AMD's don't mine well (in comparison to Nvidias) so right now they remain the better more flexible choice for long term usability in all kinds of alt coins. What I'm hoping we'll see is more and better custom built cuda miners that take advantage of the extremely high GPU clocks of Nvidias in some way I can't really think of.
Anyhow, the point of this mental exercise is simply as SighTurtle stated;
Well that scenario sounds horrifying for anyone wanting a Vega card.
edit: For gaming.
Yeah, absolutely, I think the midrange Vega is going to be a mining beast with extreme efficiency once those clocks are dialed back to match the sweet spot on the Glo Flo fabrication process. Because we all know it's going to hit the market already wrung out with no head room to go up, that means going down and it'll still probably slay all the other GPU's out there in consumer land as far as mining goes. So launch prices are going to suck, they're not going to drop and availability is going to be painful - unless the mining market suffers a horrible doom between now and launch.