Considering the GT has barely dropped over the past 13 months, I personally don't think the 6800 line is ever going to get cheap. I'll believe it when I see it, but 0 availability for 6 months, followed by limited availability at >MSRP for 4-5 months, followed by FINALLY going sub-MSRP almost a year after launch has made me a cynic.
It's why I skipped the last generation.
Of course, I'm talking about PCI-E. AGP is a different story, and is already more reasonably priced. But since the 7800GTX is PCI-E only with no plans at this time for an AGP version, it should have almost zero effect on 6800-line AGP pricing, so I hope you're asking about PCI-E here or you'll be disappointed when the prices don't drop any faster than they did before the 7800GTX launch.