I dont think Sony is naive enough to think Gaas is the solution.
What they are doing, us expand their library. During the PS3 era, they had a lot of great mulitplayer games like Resistance, Killzone, MAG, Socom, Warhawk and Starhawk (as well racers, but there's still GT).
But last-gen, they were focused on singleplayer primarily and we've seen some mp studios close, like Zipper (Socom/MAG) and Icognito (Warhawk/Starhawk).
So rn they have almost only singleplayer and practically no multiplayer.
So the way I see it, is that they are going back to what they once were a more allround publisher with less reliance on 3rd party multiplayer.
It's an investment that they have to make now, to be less dependent going into next gen.
And to so that, they acquired new studios that were already working on projects, hence why we see titles like Concord, Marathon and whatever Fairgame$ is working on, rather than a new Socom or Warhawk.
(And GG and Insomniac are already working on multiple titles, so they have little room for a new Killzone or Resistance).