Well inFamous has already sold around 2 mil retail. Add that to the already downloads, it probably sold around 2.5m. Add that to future purchases. I think at least one mill gamers will download it for free and/or bu the game in the future. I think inFamous is going to reach about 3.5 million homes ( About 2.5m of those being retail sells).
I think inFamous 2 will do much better than inF1. It see it selling around 3.5 million. I don't it'll reach 5.0 million.