I'm saying these absolute WORST case scenarios
The PS3 refuses to drop it's price early enough and follows the GC track it's whole life : 20 million
The Xbox 360's sales decline continues, and for whatever reason Halo 3 doesn't pull it out of the spin: 30 million
For some reason, hidden to the logical mind, the casual consumer stops purchasing the console with the most games and the Wii's sales sit at what casuals it picks up over the next 2 years plus the few to the end of the generation: 50 million.