Just a quick post but I thought it was worth considering:
Sony will want as many people as possible to experience PSNow and so it makes sense to give SOME people access to a limited library. They can kill two birds with one stone by offering 2 - 3 PSNow games a month to PS+ subscribers, playable forever as long as you're subscribed. They'd be able to offer classics from the PS1 and PS2 era as well as early classics from the PS3 era. Even those that have already been on PS+ would be welcome because a lot of people missed out on them earlier on. With PSNow/PS+ Sony has lots of wiggle room to compete with anything EA or MS come up with.
Just to make this clear:
Vita (two games) monthly
PS3 (two games) monthly
PS4 (two games) monthly
Vita/PS3/PS4 (two to three games via PSNow) monthly
The PS5 Exists.