SCEE’s Senior Vice President, Michael Denny, seems to have put his foot in it. In an interview with Silicon Republic he quite clearly lists Gran Turismo 6 amongst a list of games coming to the PlayStation 3:
"Look at the games coming out on the PlayStation 3 this year like The Last of Us, Beyond: Two Souls, GT6."
He mentions Gran Turismo 6 without any hesitation whatsoever as he lists off a number of first party exclusives headed to the console this year.
It's a possibility that isn't as remote as it might first sound. Gran Turismo 6 has actually been in development since 2010, so a 2013 release isn't out of the question, despite the lack of information thus far released for the title.