*Most* people are stupid in this lovely world.
Nintendo's only reason to abandon Wii early would be if their internal devs felt they hit a wall in developing for it and they thought a new console could best continue their market momentum.
Logically it makes no sense right now to release before the others as Wii is #1 in sales consistently which proves it has the most consumer demand, regardless of perceived hardware limitations by fanboys.
I firmly think the next gen will launch in 2012. These may be initially presented as early as E3 2011.