No one game will be a huge sales booster for the PS3, it is apparent that this is the case now. You could pick a handful of games being released over the next year that could boost sales, but there needs to be a price cut at the same time to boost the hardware sales.
God of War 3, Uncharted 2, Final Fantasy XIII are all games that will boost sales, but Sony need to realise that a price drop as well as a new game being released is the best way to kick start a huge hardware boost.
They had a chance with LittleBigPlanet and latterly with Killzone 2. But they haven't dropped the price of the console in nearly 18 months, so a price drop certainly is required.
To get the most impact, a price drop in Japan at the same time as FFXIII releases will make a difference. As well as a price drop at the same time as GOW3 released in the West.
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)











