The GT300 is rumored to begin shipping later this year, but if these reports are true, and AMD doesn't face a similar setback on the HD 5800 series, Nvidia could be in some serious trouble. It's one thing to have stiff competition -- but having no hardware with which to compete is entirely different. The 5800 is supposedly on its way -- what does Nvidia have planned to counter it?
Poor yields haven't always affected the market negatively. When Intel began seeing failures on the more complex L2 cache of the early Pentium 2, they decided to disable the cache and sell the CPUs anyway, giving rise to the Celeron. Rebranding duds as less potent chips has since become a common practice for manufacturers -- but that's probably not an option for Nvidia in this case.