Sony doesn't need to buy studios, they need to create new teams inside the studios they already have. Create teams inside the same studio is a much better aproach for someone whit as many studios as sony since costs are lower, the teams can colaborate to deliver more polished games and the studios "pedigree" ( that naugthy dog logo make the game way more attractive ) can be used to generate more sales for new ip.
Exception: If a big name developer, like kojima, comes to sony and ask for a new studio, than sony needs to create a new studio for this guy! "kojima" level developers are rare and sell games by just putting their names in the credits, if they wants to work whit sony exclusives sony must create a studio for the guy or colaborate whit it to create the game.
Prediction: In 5 years Nintendo will Lauch a "Core Mario game" very similar to Astro Bot. That said, many will Ignore Astro Bot existence and say Nintendo created this concept.