It's also interesting you didn't mention LittleBigPlanet. It's definitely not a guaranteed success, but I think out of all the games coming out this year, it certainly has the most buzz in the gaming world. If Sony can get some mainstream news companies to cover and hype the game (ala Nintendo), it could keep the system competitive with the 360 all on its own.
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
