I don't get why people shift the discussion entirely to what's going to happen rather than where things are now. We got some interesting numbers, I think Fable 3 is doing rather well and Halo Reach is a beast. As to GT5, it's probably too early to tell, but I doubt it can top Reach numbers overall as some seem to believe. There is no, one game sells differently than others, games simply sell differently per generation. This generation sees more sales in the first few weeks of a game's release than any other time and I don't think it'll change per game.
We have a more mature industry with a lot of talented developers and soon after a game has been released, we get a similar one that is new and steals the thunder from past games. Development cycles are getting shorter and it's harder for games to have long legs, some still do but it's still not comparable to first week numbers.
