kain_kusanagi on 05 January 2013
Since the PS3 dumped it I doubt Sony will bring it back on the PS4. All signs are pointing toward the PS4 not being PS3 compatible so it's very possible that the PS4 won't even bother to play PSX games either. Sony may decide to go with some kind of Virtual Console type of thing rather so they can sell us games we already own instead of letting us use our own discs.
I keep the systems I buy forever so backwards compatibility is more of a convenience thing for me. But if the PS4 doesn't support it I'll just keep using my older Playstations for their games. It's not a deal breaker.
