No killer game? There have been plenty of strong PC releases recently just this past year. Portal 2, Total War: Shogun 2, Crysis 2, Deus Ex: Human Revolution, The Witcher 2, and Dragon Age 2 all put a significant focus on the PC version and pushing what PC graphics can do (I do not believe that having a console version and putting effort into it automatically makes the PC version a "console port"). We have Battlefield 3 coming up, Arkham City, Skyrim, and hopefully Rage will have cutting-edge graphics once they get their act together and release the high-res textures. Plenty of reasons to upgrade. The reason it's taking a while for the next GPU generation to be released is that both AMD and Nvidia are having problems moving to 28 nm processes that allows smaller die sizes proportional to amount of transistors, making them more efficient and less expensive. They could -- and did, in AMD's case with the 6900/6800 series -- put the chip designs for the smaller process in the current 40 nm process, but they have to keep prices up. Making a more powerful chip at the current process would be too expensive so they're focusing on moving to the next process to cut costs and improve performance across the board.
And people have been all doom and gloom about consoles replacing PCs for more than a decade; I see no more reason to believe it now than there was then.