Well, the sweet spot on a 480 is around 1125 with tweaked memory timings and clocks and that pulls ~ 32mh/s so the core is only utilized at around 75%. That would mean a 480 is capable of roughly 43mh/s if it wasn't memory/thermal/power constrained. Efficiency would of course go right out the window.

Using that same math I'd figure that full on 4096 Stream Processor Vega should pull around 77mhs or so if it isn't memory/thermal/power constrained. That's also assuming AMD hasn't added some secret sauce to bump mining efficiency.

That being said, I'll believe it when I see it. AMD hasn't exactly delivered when it comes to their GPUs and really has been disappointing back to the 200 series.