That might be true, but you're looking at a very short period. In terms of games released, HZD is one game after years of other things. Who's to say Guerilla will continue along these lines? Is that a mandate from Sony, "thou shall't only make single player cinematic games?" It's already bee n raised multiple times in this thread that there's a lot more to Sony exclusives than that.
Your argument seems to be that only large, single player games count as exclusives, and Sony is knuckling down on those and eschewing the rest. I don't think it's proven that's the direction Sony is headed, nor that it's the way they should go. Previous PS's sold gang-busters because of the library diversity and something-for-everyone. 10 million selling GOW and HZD may sound awesome, but if you're selling to the same buyers, that's only one eighth of the audience that cares for those games and the rest want something else. If Sony are going to focus on exclusives, they probably need to stick with diversity. It'll be interesting to see if in ten years, the only things coming out of Sony's stables is wide-linear single player story games as you are suggesting.
The diversity is existing mostly from game coming from Housemarque, Quantic Dreams, Media Molecule, VR games internal or external, Japan Studio, japanese third party exclusives.
They know long tail is important and they have the advantage to be a global brand with Playstation not an anglo saxon one like Xbox.
I never said than diversity is not important but big exclusives are important too and sold 10 to 15 millions for a title is very good too and they not only sold to the same people for example HZD sold probably to more woman playing games than God of War because they can identify with the heroin. And God of War sold better than other exclusive in US. It is not the same 10 millions everytime.
Playstation is God of War, Horizon Zero Dawn or The Last Guardian, Resogun, Alien Nation, Helldiver, Singstar, Hidden Agenda, The impatient, Dragon Crown, Detroit become Human, Death Stranding, TLOU, Dreams, Shadow of the Colossus Remake, Gravity Rush, Bloodborne, Ghost of Tsuhima, Infamous, Ratchet and Clank, Spiderman etc.
From third party, Nier Automata, Yakuza, Ni No Kuni 2, Persona 5 etc.
It is not like Sony miss diversity and they do the things right they are on the road to sold more than 100 millions home console for the third time, never done by Microsoft or Sega and only one time by Nintendo.
Edit: Out of God of War, Uncharted, TLOU, Gran Turismo(not the case now), Little Big Planet and now Horizon Zero Dawn no Sony games were massive but they continue to work with the same studios if they fit inside first party strategy. And it is impressive for AAA studios because the cost is huge not like AA title.
They close everything linked to racing game out of Polyphony because not enough sales and same things for multiplayer games or online oriented game better served by 3rd party with Destiny, Fortnite, Overwatch, Call of Duty, Battlefield, Battlefront, The Division, Ghos Recon Wildlands, Rainbow Six Siege etc. And it is a better strategy using third party marketing and the 3rd party are probably happy to work with a platform holder not trying to make the same type of title.
Edit2: But exclusives and 3rd party games are only a part of the success of Playstation for example last generation Xbox gains a little ground in continental Europe because Sony sold a too expensive product and too late. But Xbox lost all the ground Sony launching a product at the right time and price. In continental Europe the biggest advantage of Playstation is Brand not games but it is another advantage for the core gamer the more sensible to game quality.
