I don't think Install base matters that much.
I mean, once you get a fairly big install base. Say about the level the 360 and Wii are at... you've got a lot of your "hardcore" base in.
So i'd expect a lot of hardcore games to sell the same. I mean Brawl is going to appeal mostly to Nintendo fans, who, likely owned a Gamecube last time, minus the ones who want the new characters or were brought in by Melee's hype.
Halo 3 is mostly going to appeal to Xbox fans who had the first Xbox, minus the people brought in by Halo 2 and the massive hype machine microsoft built up.
I expect Halo 3 to sell about a Half million more. Could be wrong who knows.








