1070Mhz Core clock and 2x 8 pin PCIe power connector imply it's a normal Hawaii TSMC spin. No power savings there, move along.
It implies that Grenada (whatever it turns out to be) is pin-compatible with Hawaii and that Asus just reused the existing board design. It doesn't necessarily mean that the silicon is exactly the same. There is no reason that a GloFo redesign could not use the same pinout; in fact, the board partners probably wanted it for precisely this reason.
Asus has a history of sometimes being lazy with their designs. When they created the R9 290 and 290X DirectCU II cards, they simply
re-used the cooler from the GTX 780 series, and only three of the five heatpipes made contact with the smaller Hawaii chip's core. This is why the Sapphire Tri-X cooler, which was designed for AMD chips, did much better. It's also disappointing to see Asus carry over the old port layout into a new design; we really should be done with DVI ports at this point. 2x DVI and only one DisplayPort on a 2015 design is a very poor decision.
One thing is for sure, if this is indeed just a rebranded TSMC Hawaii chip, then the $449 price cited in the Tweaktown article is a fantasy. Who in their right mind would pay that? The R9 290X is available for under $300, and these cards can already hit the 1070 MHz clock speed. 8GB of RAM is going to make absolutely no difference unless you're running two of these hypothetical cards in Crossfire on 4K, and that would be an incredibly silly thing to do when a single GTX 980 Ti (and probably a Fury X as well) would provide better and more consistent results at a cheaper price. Past tests have shown that Hawaii isn't bottlenecked by RAM bandwidth, so increasing the RAM speed from 1250 to 1500 MHz is also not going to provide a substantial boost in actual performance. If this really is just a R9 290X rebrand with more RAM and factory overclock, then it is going to get slaughtered by the GTX 970, which offers comparable performance at HALF the power usage... and much cheaper! AMD can't possibly think they could get away with doing something like this.
Of course, all this assumes that the slide is genuine. Such a thing could easily be mocked up in 30 minutes by almost anyone, so we will have to wait and see to find out to what extent it is accurate.