I know the PS4 doesn't have any backwards compatibility, but the PS3 was able to play PS1 games and that didn't have backwards compatibility either. If you put a PS1 disc into the PS4, will it let you play the game without needing to pay for anything on the Playstation store?
I don't believe it is possible. Sony seems to be waging a war against backwards compatibility by wanting to push people to the PlayStation Now service. I doubt the PS4 will ever be able to play Ps1 games.