There is not going to be a 10 year plan. Look at the PS2, it stopped being great after 8 years. It's still going reasonably well, but it was always popular.
I completely disagree with your statement that the PS3 will have horrible sales in 2009. It will have better sales than any other year. The price will go down (If only slightly) and a huge wave of incredible exclusives will come (GT5 says hi).
I think they will make the PS4 in 2012. Games could keep coming out for the PS3 as late as 2014, but by 2012 it will be considered last gen.
PS-PS2 = 6 years
PS2-PS3 = 6 years
doesn't it follow that PS3-PS4 = 6 years?
I am aware that the PS3 has not done nearly as well as either of these, but it can hold out for another 4 years, easily. Maybe more. And there will be enough good games by the time standalone GOOD blu-ray players become cheap, that the PS3 will no longer be a "blu-ray player that plays games" but a console that happens to play blu-ray.
(Former) Lead Moderator and (Eternal) VGC Detective 
