IMO judging by what they said during the financial analysis day concerning price to performance ratio (and we can ignore current prices and assume they were talking about MSRP prices coz this was before the mining craze that bought up prices), there are only 2 ways it can go, either they were aiming for 1080 performance priced as a 1070, or aiming for Ti performance at 1080 price, now considering the size of the die (even though we haven't got an exact size yet) which is bigger than GP102 no matter the exact dimensions, HBM2 being more expensive, and a beefy power delivery system being necessary (and they uses quality components on their vanilla cards), it seems highly unlikely that it will be priced at 1070 MSRP unless they have managed to use some magic pixie dust in order to reduce costs of a monolithic die (highly unlikely, and to my knowledge unheard of on a brand new die), so I can only deduce that they were at that time aiming for Ti performance while being priced as a 1080.
IMO for the RX vega to be priced the same as a 1070 it needs to have either a modular die design which would highly surprise me even though Vega is infinity fabric capable, or a smaller die with less transistors, but nothing seems to indicate that except that there seems to be a ******** of transistors on the Vega FE doing **** all at the moment when it comes to gaming (or only being useful for productive loads) and using a hell of a lot of power to power nothing lol!