Both, the Playstation 4 and the Xbox One will not be backwards compatible with any of their predecessors due to a complete change in hardware architecture from PowerPC to x86. However, at the initial Playstation 4 unveiling back in February, Sony suggested that it might have at least a partial solution to the problem in the guise of Gaikai, the game streaming service that it acquired a while ago. While speculation has been rife since then, we haven’t had any official word. That changed earlier today.
In addition to streaming Playstation 3 games (which will serve to provide backwards compatibility with the PS4′s immediate predecessor), it has now been confirmed that Gaikai will also stream Playstation and Playstation 2 games. Gaikai streaming still does not have a date, with Sony confirming only that it will be available on the PS4 sometime ‘after launch.’
As of right now, we have no idea how Gaikai will work- will all titles be available for streaming for free to, maybe, PS+ subscribers? Will Gaikai even be offered on a subscription basis? Or maybe titles that you already own on PSN will be offered on PS4′s Gaikai? Stay tuned for further developments.