In an interview with gamesTM magazine, The Last of Us developer Ricky Cambier stated that the PS3 is still an "Exceptional piece of hardware". It is currently not known if The Last of Us will be Naughty Dogs last project before moving on to the PS4:
"It is toward the end [of the console cycle] but we are still pushing the hardware,
We bring that clear to the players and to the expectation that the PS3 is still an exceptional piece of hardware. Even at this stage we are finding new ways to push it. I think we benefit from that.
It’s just kind of fun to look for ways that we will take the tech of the hardware and take the needs of the game, and look for ways we can push [the hardware]..push it in ways we’re still not seeing in the games industry."
The Last of Us will be released exclusively for the PS3 on June 14th.