Personally i think no. I won't bother going into too much detail as have done that in the thread in my sig. But i think people are expecting way too much with GOW sales. There have been higher profile games that have sold far more then GOW and have had little effect on sales this gen. The same can be said with FFXIII. People are forgetting that the game is already out in Japan where it is exclusive. If we look at it's 2nd week totals in Japan i think it put's it near the bottom of opening sales for a final fantasy proper game. The game is multi-platform everywhere else so when that is released you have to say a lot of people who would normally buy a PS3 for the game could go for the 360 version, especially in NA. Meaning the sales that it would of got if it remained exclusive will not happen.
The one remaining game is GT5. If the game is as good as we all hope then it will do very well especially in Japan and here in UK. But as the year goes on towards the end i can't really see anything that has the potential to shift more hardware at the same rate as say GT5.
That is why i think 2009 will be known as PS3's best selling year. I think this year will see the peak of 360 too. And then the gen will just gear up for the next one in the next 3-4 years.
History has shown that the first 3 years are normally the peak. This is not a normal gen so will be interesting to see what happen's.