There are a lot of PS3 exclusives that are being mentioned that are not going to move any systems. Killzone didn't make much of an impact on the gaming world so why would the second one? The only other game the makers of Heavenly Sword have made is Kung Fu Chaos, which sucked.
Let's look at what the most anticipated games on the PS3 really are: http://www.gamefaqs.com/poll/index.html?poll=2748
So we've got:
Final Fantasy XIII - Exclusitivity is now under discussion: http://www.gamespot.com/news/6167864.html?action=convert&om_clk=latestnews&tag=latestnews;title;1 . When 3 times as many people own an Xbox 360 and Final Fantasy is huge in the U.S. then they would have a lot to gain by porting it to the 360.
Metal Gear Solid 4 - Kojima said a port wouldn't happen but ultimately it's Konami's decision. Remember, MGS was released on the PC and MGS2 was released on the PC and Xbox although Kojima didn't want it.
Grand Theft Auto IV - On the 360
Devil May Cry 4 - On the 360
Assassin's Creed - On the 360 T
wo others not on the poll but definitely on the list are:
Resident Evil 5 - On the 360
Grand Turismo 5 - Exclusive
As you can see the anticipation for Lair and Ninja Gaiden Sigma are limited. Only 3% of people voted Lair even though it's coming out soon and it's one of the ones that people on boards mention over and over again. I doubt either of these games will increase the PS3's sales past an initial boost like what Motorstorm did. I do see the boost for Lair being a little bigger than Motorstorm, however, but the PS3's sales will probably drop down to normal soon after. T
That leaves 2 uncertain exclusives and one certain exclusive that are really system-sellers. Judging by this poll: http://www.gamefaqs.com/poll/index.html?poll=2749 the 360 has Halo 3, Mass Effect, Fable 2, and Blue Dragon as the exclusive system-sellers and then it has all the non-exclusives that I mentioned. Basically, the 360 has more system-sellers than the PS3 and it's actually popular and it's $200 cheaper. Plus it won't be too long until the price drops.