No way to tell today.
Those who know price or performance are under NDA.
All others are guessing.
A new gen of graphics cards will have either a better top end performance level(expect those to be very expensive)
Or, the maker can use smaller mfg tech to lower their costs.
Regardless, expect the cards to sell for what the traffic will bear.
Do not expect the old versions to plummet in price. Yes, there will be some clearing of old inventory. When that is done, the new retail price of old gen cards may well rise.
That is for those who need an identical card for a sli/cf upgrade.
On the used market, you will see cards sold more on a price/performance basis.
What to do?
If you have a need for a graphics card now, go ahead and buy...