Correct, ATI will price new card accordingly, it if beats GTX 480 it will at best case cost the same and most likely more.
If its slower than yes it will be cheaper, but if its slower than its gonna be an epic fail.
Why is this the current thinking, its madness. 280gtx, 15-20% faster than a 4870, 280GTX £350+, 4870 launches at £180, was that appropriately priced compared to Nvidia, no, was it a market share play, partially, was it mainly down to a fair profit based on cost to produce, yup. Was it because they can sell 500k £300 cards, or 5million £200 cards, yup.
THe 5870/5850, on launch, the 4890 was £150 ish(it was back up from its low) the 285GTX was back up at £300, so the 5850, which spanks a 285gtx badly, was priced massively below it.
AMD do not price based on Nvidia prices, or Nvidia performance, they price based on the best ratio of profit to sales they can produce, its really that simple.
6870, £300, 6850, £220-250(depends how cut down it is), new 6770(old 5850) £170-180, new 6670(probably a 5770 with higher gddr5 speeds so less bandwidth limited) £120-135.
With probably a few parts filling the gaps, 6750 around the £150 mark, a 6830 around the 200 mark, a 6650 around the £100 mark, etc, etc.
The only die likely to get bigger is the top end die, the 6770 will be a smaller and cheaper to produce 5850.