I think the view from their side must be, better risk loosing some console sales and keeping some customers on any hardware (keep in mind, they had phones that ran PS1 games too... so they're open to become platform agnostic).
They could go even further and port their PS4 APIs and store to windows and make their own platform, like steam, run natively on PCs (depending how thightly integrated it is to the underlying hardware).
Yet, if you care for image quality at all, PSNow will not satisfly you, try looking at some videos of your favorite games on youtube or twitch by example, the quality is horrible and if the game is 60fps you loose half the frames... it really breaks some of them completely, I am personally not interested in it, not the least bit!
I would much rather have up ports, like The Last of Us or Thomb Raider:DE on the new consoles, to run the games better than their original versions, or emulators that run the games locally, potentially upgrading the resolution at the same time, like on PC (Sony supposedly has developped one for PS4, we are just waiting to see it in action, if this is real).