Wii has sooooo much backup tactics left that it's incredible. While both PS3 and X360 have used pricecuts and bundles(ok 360 not as much as PS3, especially in europe), not to mention various SKU-s.
Wii hasn't used ANY of those yet. Imagine, sales become stagnant - Wii for $199, new colors, USB flash disk+some other new functionality
Just imagine WiiFit+WiiSports+Wii bundle for $300. Now advertise it in some lifestyle magazine === massive sales. Not to mention that every other gym would buy those
.