The way I see it, the longer this generation lasts, the better the next generation will be.
I mean look at a 1 year difference between computer hardware, The Radeon HD 4000 series and the HD 5000 series, power doubled in 1 year. Wait another year, and there will be another large increase in power.
If they have their consoles ready to release by 2012, but instead release by 2013, they could have a drastic drop in prices and can launch their consoles for a profit unlike this generation, which I felt was rushed and too much of a power increase, all while still profitting from current generation hardware.
Another interesting thing is, I think the Wii to the next Nintendo console will have the largest graphical leap in video game history, depending on when the new consoles release. While 360 and PS3 will have some of the smallest graphical leaps in video game history.