I think this is it.They are most likely not ready to make that commitment due to infrastructure (they do not have cloud servers just readily available, PSNOW is not even available in alot of countries due to this), risk aversion (they are not as big as MSFT, GOOGLE, AMZN so any risks that fails hurts them more.), Market leader (they have a profitable, winning formula and marketshare, probably want to milk it as long as they can) and long term viabiity (current and future profits from game streaming need to be able to justify the full commitment.)
I think well see PSNOW get more attention this gen but i can't blame them for being timid on giving up 70 dollars a pop on guaranteed 5-10 million sellers like GOW, TLOU, Horizon etc. Same way movie theaters are reluctant to put AAA movies on streaming, day one. At the same time, cant get complacent either and you have to look towards the future and what the competitors are doing. Its a delicate balance.
But there could be more to it. They pushed PSVue and you used to see ads for it, but it failed even tho the quality of the service was great. I don't think they're confident in the quality for PSNow for them to go all in with it like their competitors. Subscription based models in game is the direction their competitors are going. We might look up one day, and those same competitors might be bidding on copping Playstation from Sony.

Apple is gonna make a move eventually as well.

