From Software and Insomniac are too big to be bought by Sony I think (even if they were up for sale). Reasonable acquisitions would be:
Kojima Productions, since Kojima was always in good terms with Sony and they are not only publishing his game with his new studio but they also allow him to use the Decima engine.
Bluepoint Games. They are not very big and they predominantly have always made Sony games.
Supermassive Games. Same reason as above.
Other than these (and these above are a big if) I believe Sony will continue to expand their current studios (and they are already doing it). For example if Naughty Dog can be expanded enough so they can work on two projects at a time, then they can release two games with the brand Naughty Dog on the box, and that is a big seller, as opposed to one Naughty Dog game and a game from a lesser known (and prestigious) studio. The same can be said for Santa Monica Studio, Guerilla Games, Polyphony Digital and Sucker Punch.
