Both consoles have the advantage, for them not us, of not being backward compatiable. So unless people who don't own a ps3 or 360 already have no intention of ever sampling that generation, than I think both consoles can count on many more future sales, besides if they make X amount, they can count on eventually selling them even if they let them go cheaply.
With all that said, why is it solely hardware that wins a generation in terms of sales. While the Wii is currently leading in software, for the 20 million more consoles it sold over the 360, the 360 seems to have sold more games per console than wii has, like 360 owners buy more games. I think the 360 will definately win this generation in terms of software sold of the 3 consoles. Maybe that doesn't matter to some, but I think it tells you has much it's owners invested in it after they bought it.