there is no reason for them to back off if the competition is weak. if they spent a hundred million making kepler, they loose millions with every day they dont launch it. right now a card twice as fast as a 580 would be worth 800$+, in a few months it might be worth only 500$

if they had both cards ready, they would have released both cards

my take it that they learned their lesson with woodscrews and large chips thanks to the fermi situation and decided to launch their 460/560 type part first, since thats where most of the market share can come from. however due to their timelines, or thanks to competition, they have the ability to call it an upper level part. the fact its called a 680 means their large gpu is still a long ways out and/or that it competes with the 79xxs. it dosnt even have to be faster than a 7970 either, since they might get a whole bunch of sales thanks to people who have believed thanks to their track record that its faster than the competitions high level because they usually are.

i think nvidia has played it very smart this time around. the only thing we wish they did was show up, or atleast give us real press, when amd launched their cards. too much silence when your running late usually means you have not much good to say. imagine if they gave us one teaser add a few months ago saying, "hold on, we have something guaranteed faster and/or cheaper coming" and by that late in the game they probably could have said it too since they would know where they stand, and they set their prices. but instead they let competition soak up some market share, which i dont think was very smart.