No. The 6990 is an exhibition card, produced just to prove they can. It will be very hard to find and very, very expensive. It will have no impact on 6950/6970 prices, because it is not competing anywhere near that price point. It will only be competing with the GTX 590 in the ultra-high end. Price points will be determined by the competition with the GTX 590.
AMD HD 6990
"You may or may not be aware that the upcoming dual GPU from AMD is almost here. Over at the MSI booth they actually had the card displayed in a cabinet. Of course there were no details at all regarding the specifications of the card due to everything still being under NDA.
What our MSI rep did reveal though was that this card will be in very short supply due to the card being an attempt at showing consumers this is what is possible “cause we can”. Its merely a card to show sheer power and is likely to retail for a lot of cash." http://www.vortez.net/articles_pages/cebit_2011_msi_mil...
I remember how the 7900 GTX Duo went, the 6990 will likely be all the same extremely expensive and rare. The GTX 590/595 will be no different. I personally had a few runs with dual gpu cards and they are often very flaky at best most of the time.