So far the AMD marketing direction is that vega is an improvement over previous AMD cards. I have never seen a concise explanation on what the 5XX series was improving
Keep in mind that video cards are aimed at GAMING as their primary market, not mining.
The 5xx series moved to a slightly different process on the same node, that gave the ability to clock them higher at a minor cost in efficiency.
I don't see the VEGA being a killer card for ETH/ETC and such mining, as it's still HBM and like the Fury line HBM has a lot of latency that hammers ETH hashrates.
It SHOULD be a highly effective card on other mining though, like ZEC where the Fury line IS a good at mining.
I can also see a high probability of it taking AMD 2 or 3 driver iterations to get a "good for mining" VEGA driver available.
Don't compare the Vega Frontier Edition for $ - it's a workstation-targeted card (like the AMD WX line) and those are ALWAYS overpriced compared to consumer cards.
(compare the WX 7100 to the RX 480 and RX 580 - slower clocks, single-slot, but it's higher priced than even the current GOUGE pricing on the RX equivalent cards).
Also, AMD has already specified that there will be at least one "gaming" card with higher performance - and that will probably cost a fair bit less then the Frontier Edition.
The consumer "Vega" cards are widely reported to be due for "release" as SIGGRAPH at the end of this month/early August - but no firm word YET on if it's going to be a "paper" release or if the cards will actually be available for sale at that time.
I suspect it comes down to "has Hynix gotten the production issues with HBM2 fixed yet".