It doesn't have to do anything except run PS5 titles better, and it's well positioned to do that with PSSR, I think (making assumptions on quality and suitability). Devs won't target it at all. It'll just be a compile target for the PS5 game. So all it'll do is run PS5 smoother in better quality, and that'll be enough for those who are just buying the bestest PlayStation. There are a good few 10-20 million who have these boxes for online gaming, Fortnite and COD et all, who'll be happy just to have better quality.
It won't sell in volumes. It'll run a nice halo effect (all future PS5 marketing using PS5Pro visuals) and cause a hardware ripple-down which'll help the total PS5 install base. It'll do exactly like a new high-end GPU does for nVidia or AMD. My only concern/curiosity is what it takes to put this together and what it'll need to sell to make its money back (at whatever margins)?