There's nothing Sony needs to turn the tide since :
- PS3 outsold 360 before the september price cut worldwide, and so it will do it again as soon as Sony cuts the price. It sold more from launch than the 360 too if you look at vgchartz hardware sale from launch
- most exclusives are now PS3 exclusives, and the 360 ones are coming to PS3 too (Ninja Gaiden 2 Sigma, see yesterday announcement)
- you can't buy PS3 exclusives since they're Sony owned (or Konami but they don't care about the 360) and they dominate (LBP, Killzone 2, uncharted, Ratchet, Motorstorm, MGS4)
- 360 has not so many exclusives planned now compared to huge games like Gran Turismo 5 or GOW 3
Ultimately, I think the PS3 will easily win this gen in installed base. People doubted they would for the PS2, and look where they are now.
After all, installed base is already on par in europe, and 360 is dead in Japan...