The 7nm part should give upto a 10% speed boost over current VEGA 64, probably on average 5-7% not bad. No idea on pricing as current VEGA is highly subsidised by AMD, they make a loss after funding the current lower sell prices so hopefully any re-spin they do can hopefully reduce their manufacturing cost considerably as sell GPU at a loss only leads in one direction and they can't rely on CPU to keep their head above water always especially now as they are pricing CPU more aggressively.
We shall see as it stands now VEGA 64 at £449 with the games bundle is a good offer as the 64 should comfortably beat a 1080 in most titles, particular higher resolution and cost around the same.
The real pick is the Powercolor card as its probably the best VEGA 64 on the market if your case has enough room for the monster that is the Devil cooler.
For me where VEGA is a clear win is with the whole FREESYNC support and the fact you can buy 4k FREESYNC monitors for around £300 or high refresh rate 144Hz 1440P panels for also about £300, its the whole monitor side of things that is keeping AMD quite a strong choice in the gaming community. Of course the fact they are quite strong at mining helps too if your into that to recoup some cash.