I don't believe any release dates that Sony confirms, especially for Gran Turismo. GT5, Last Guardian, The Last of Us 2, HDMI 2.1 for their TV's... just to name a few popular ones. Unfortunately delays are very common nowadays, not only for Sony but for other publishers as well. They just go for the publicity and marketing.
I'll somewhat agree on the basis since we see a lot of publishers announcing gaming years or months earlier than the games are actually ready (beyond imprivisible events of course) especially for most of the AAA games recently.
Publicity wise, you'd of course want to announce your bigger guns early cuz it gives the promise of this bright future and the worthness of an early investment in their console.
Still, if Sony manages to make all these titles announced, ready in it's first year, I'll have to congratulate them just like I did when Nintendo hit all those heavy hitter in the first year. Could say they may have taken a chance with this strategy since it had been succesful enough for Ninty. I mean a lot of these titles became the flagship titles and evergreen on the platform. Sony is bidding for a similar result I think.