Is there really much interest from people to play these old games to make this viable?
I mean most of the PS1 games have aged badly, same goes for PS2 games. PS3 games are more relevant but most people will have already played them etc.
Personally I would struggle to list half a dozen games that I might revisit and even then I wouldn't want to pay much for the privilege.
I can see this type of service being good for new games if you have good enough internet. Playing PS4 games with only a TV and internet connection for example, however just to play an arguably weak back catalogue I don't really see the point in it.
PS4 games will also be available in the future:
http://www.computerandvideogames.com/444296/ps4-games-in-the-pipeline-for-playstation-now/
Which is probably why Gamestops shares fell 10%