Nope dude. The 3870 was a mid range card slightly slower than a 9600GT which was a mid range card.
Initially AMD wanted to prove to people that ATI just got better and thus the low pricing to make a come back. With the 6900 series, AMD has already proved that it is good, very good.
The 7900 series is in a league of its own and doesn't need any more convincing for people to buy.
Rest assured, you can expect future AMD cards to be priced around the $500+ mark for their high end stuff, in the coming years.
That proves my point. They are going with a different pricing structure onwards of 7xxx series like they did till 2900xt and before that.
The golden days are over and no matter what nvidia does (and I assure you that it won't be much cheaper than AMD if at all), AMD will have high prices from now on unless they screw the performance with the next gen cards, which is rather unlikely.
And just for your info, your post makes 0 sense
Whenever a next gen card launches, it is supposed to be 20-50% more performance at the same price point. Not similar performance at a similar price point.
Check any card in the history of the universe. A next gen card is typically the same price and much much much faster, not similarly priced and just a tad faster. If they don't want to launch a new card because of lack of competition, it is cheaper to scrap anything apart from the 7900 series altogether as nobody from a 6900 series will go for a 7800 series any way.
So you don't even know what your talking about