Id rather they get something other than Gearbox but I agree. They need to buy someone with some already established ips
Either that or buy studios that can help produce more 1P AA and AAA games with the IP they already have. SIE have a lot of solid IP, but a lot of it isn't suitable for their modern AAA cinematic stuff. And they don't seem to have enough teams among their current studios to handle all those IP possibilities in reasonable time tables (not to mention, redundancies in budgets for certain AAA games and GAAS titles eating away at would-be budgets for these other games).
But if anything, they need to develop more 1P AA content, maybe with a different label like PlayStation Artisans or something, and grow the AAA studios some more while taking some different approaches to releasing certain AAA games. For example, designing the game as hefty "parts/installment" type expansions released every couple of years at a lower price per installment/part. But, make each one feel like a game unto itself, like the FF VII remake trilogy, or Shining Force III Scenarios 1-3, or Uncharted: Lost Legacy.
SIE's biggest problems right now are they don't have enough 1P internally-developed non-GAAS games getting made (or co-developed 1P/3P titles) and released exclusively for the console to make up for almost all of their current portfolio getting ported to other platforms like PC. And since they don't really have that many 3P exclusives (as in actual exclusives, not simply 'console exclusive') either, they don't have a lot of software to leverage as strong content differentiation towards value proposition of their console.
Like yeah they're doing a lot better than Xbox on that front but I'd argue Xbox is not even PlayStation's biggest competitor these days even if it's the most direct one. Their biggest competitors are Steam and Nintendo, despite both being more indirect (especially Nintendo). And like I've said before I understand if Sony want to leverage other platforms for some type of growth but the guiding principal of that growth should be using those platforms as "advertisement" spaces to draw those customers to a PlayStation.
That's what the original strategy for PC was and it's what they need to return to, otherwise they'll risk devaluing PlayStation to a similar degree Microsoft have devalued Xbox consoles.