Glad they're interested in acquiring new studios if the right opportunity presents itself. Although I'd be happy with them expanding their current studios too.
I've been saying for a while that they need a few more to make the balance perfect. We saw with the PS4 that the first couple years were a little rough from a first party point of view and that was largely because quality games take time. You can't rush them. And if it wasn't for the FromSoftware partnership, there wouldn't have been a great exclusive game until the third year (Uncharted 4). Any AAA game is likely going to be a 4 year endeavor, and possibly longer if you're talking a new IP, which you obviously need at times since you can't keep on making sequels forever. However, there's also a need to support the console throughout the generation. That naturally means, a studio that releases a game late generation isn't going to be able to suddenly show up early in the next generation. They will need time. And the same with those who need to support the console early in the generation. They will need to start moving to the next generation sooner, and therefore will not be able to support the current console towards the end.
This naturally means you need more teams or studios developing games in order to hit the right balance, especially because partners aren't always going to be there to help develop titles for you. If you want 3-4 AAA quality games a year from Sony first party, along with a few others to simply round it out, they'll probably need another 3-4 teams since you need to account for delays and other potential issues too. I feel like they're in a much better position than the others in providing that level of support, but the increasing demands of the current and incoming generation simply means you need more resource.