Was the OP a joke? The games stay in the shelf as long as people keep buying it. Twilight Princess is a launch game and still in the shelves, because its sales maintain a level where it's worth to keep it in shelves. Once a game stops selling, it gets phased out through bargain bin.
The shelf time is determined by how well a game sells, a different matter then again is, if the game isn't widely taken into shelves by retailers at all (NMH and Disaster got the treatment around here).
@JRPG: You know, your logic is kind of twisted. You're claiming that PS2 got good games because it could handle similar games with GC and Xbox -> otherwise the games had stayed as GC and Xbox exclusives.
In reality, GC and Xbox got ports/multiplatform games from PS2 because they could handle the games, making cheap ports possible. The market decided PS2 was the one leading the market and that's where the publishers have little to say. They are forced to go to the platform that makes them most money and earn some extra with cheap ports (in this gen, porting Wii games to PS360 isn't that cheap as PS2 -> GC/Xbox).
Ei Kiinasti.
Eikä Japanisti.
Vaan pannaan jalalla koreasti.
Nintendo games sell only on Nintendo system.
