If you notice the trend, there was a pop when most motherboards switched to pci-e interface (2003-2005).. but the second shoe dropped a couple years later with vista.. do you really think consumers would just splurge on new graphics cards for direct-x 10.X and open gl 3+?
Add to that a global recession.. and this industry will be lucky if it treads water for a couple of years. Maybe the industry will find it's footing again when Windows 7 arrives & 2gb graphics cards are common & cheap (about $100-150).
Intel and AMD already know sales of procesors are falling. Though, they still ship them and let wholesalers and retailers handle the losses.. but with $400+ graphics cards and $600+ processors, it's harder to take a loss, so you will see pushback by wholesalers & retailers if demand is not there. The high end of the market will see major reduction in sales.