If there is competetion and no mining prices will be like in fermi days.If we're looking at a full generational increase (50% performance improvement), then it will be slighty faster at 1080p and dead even at 1440p vs. Vega 56, but with half the power consumption. I see prices starting out at $649 for the 1180/2080, $499 for the 1170/2070, and $349 for the 1160/2060. If there was competition and/or no shortage due to mining, prices would probably be $50 lower across the board but Nvidia will easily be able to get away with higher prices until AMD can compete with the low end / midrange again.
Full high-end GPU(today TITANXP) for 500-600USD-Probably renamed back to GTX1080.
GTX1080 will be renamed back to x60TI card and cost accordingly-250-300usd+-
GTX1070 will be just x60 card-200-250usd
and so on..
No more Nvidia would have 70% margins and it will be again 30%.They will stil make money even with those prices...