So if Sony were to go 3rd party again, what could they offer?
Japan
Japan Studio – Ape Escape, Siren, LocoRoco, Patapon
Team ICO – Shadow of the Colossus, Ico, The Last Guardian
Polyphony Digital – Gran Turismo, Motor Toon Grand Prix 2, Tourist Trophy, Omega Boost
United States
Naughty Dog - Crash Bandicoot, Jak & Daxter series, Uncharted series
Santa Monica Studio – Kinetica, God of War series, Warhawk with Incognito Entertainment
San Diego Studio – NBA, MLB: The Show, Modnation Racers
Sony Bend – Syphon Filter, Resistance: Retribution
Sony Online Entertainment – EverQuest
Zipper Interactive – SOCOM: U.S. Navy SEALs series, MAG
Europe
London Studio – SingStar, Eyetoy, PlayStation Home with SCE Studio Cambridge
Cambridge Studio – MediEvil, PlayTV, PlayStation Home with SCE London Studio
Liverpool Studio – Wipeout, F1
Evolution Studios – MotorStorm, World Rally Championship
Bigbig Studios – Pursuit Force, MotorStorm: Arctic Edge
Guerrilla Games – Killzone series
Media Molecule – LittleBigPlanet
That's their first party studios according to Wiki. As you can see, there is a ton there.
The problem I see with them going third party is the loss of all those bits of cash they get with every game sale. I would worry that it would cause a significant shift in studio funding given that many of those teams have near unlimited budgets because their games are viewed with a dual purpose; selling games and marketing the system.
It would suck if all the sudden Media Molecule and Naughty Dog had to make their games with half the money because half of the profit opportunities are gone.