It's amazing how often people use the 'Game X has already saturated the market! No one will buy because everyone bought it already'!
For the record, it didn't work with:
Halo 3
Gears of War 2
In both cases, Sony fans assumed that Halo 3 owners wouldn't buy the system, since they already did for Gears 1. Likewise, Gears 2 had the same argument, which didn't happen, since Gears 2 brought in tens of thousands of new X360 owners on launch week vs. typical sales numbers.
Furthermore, if you want to follow that logic, I fail to see how any game you listed, save Gran Turismo 5, will move any hardware for the PS3. Uncharted 1 already came out, so did Tomb Raider: Underworld. R&C is out, and so is LBP which is a platformer too. MAG couldn't bring in new gamers since KZ2 will have been out + the ever-popular Call of Duty series.
So you have to choose which side your on, either:
1) A sequel can move hardware, even if it's predecessor is on the same system if the IP is popular enough
2) A sequel cannot move hardware, unless it's predecessor was not on the same system.
So please pick your side. You seem to want to invalidate the possibility that Halo 3: ODST cannot pick up new fans, yet Uncharted can. I don't follow how that's very logcal, given that Halo 3 sold about 4-5 times as many units as Uncharted.
Furthermore, I don't understand the Forza 2 saturation question. F2 was the first of the series on the X360 - same way with Ratchet & Clank. If F2 saturated the 360's racer market, wouldn't the last 2 R&C games on the PS3 done the same?
Back from the dead, I'm afraid.
