Sony going third party is an excellent idea for gamers.

[PieToast]

More people would be able to play more games, which is great, but there would probably be less games made all around if Sony became 3rd party.

Sony is probably not going to be interested in investing in more games, first party or otherwise, if they went 3rd party. They'd only focus on their big established franchises just like Microsoft. Maybe that's why some people want Nintendo to go 3rd party. They only care about Zelda or Mario.