I claim "There are no such things as system sellers" because "System sellers" operate quite a bit differently than fanboys think that they do ...
Most games people claim are "System Sellers" were announced (and hyped) months/years before they're released, and the release of this game is factored into the purchase of a system long before the game is released. For (roughly) 2 years people were buying XBox 360 systems who were expecting to play Grand Theft Auto 4 when it was released, even though they may have bought it with a completely different (and possibly a game that is not a "System Seller").
What this means is that when a system is released there is only a short term boost, which soon dies down, and after that you can start to see sales below the pre-launch sales if the system does not pick-up any games which are anticipated on the same level.
