It is quite improbable that the PS3 will be a "late boomer" like the PSP is. What you need to see such huge hardware sales later in the lifecicle of a console is a franchise that brings in a lot of new gamers. Monster Hunter did that for the PSP but there is no franchise on the PS3 release list that could save the console in such a way.
The PSP never sold bad in Japan it always showed decent numbers and was destined to see lifetime sales of 10 million units even without Monster Hunter. The PS3 has higher developement costs, a smaller install base, worse software sales and the weekly sales are in decline as well. There is no basis to assume that PS3 sales will spike sometimes later in it´s lifecycle, really.
The PS3 will see great Europe and decent America sales, though.







