Nintendo sells the Wii for $199 currently. What PC components would that be equal too? Pentium 2? Geforce 3? You see Nintendo is not interested in any realistic pricing at all.
The CPU is $100 and the GPU is $100. This will be selling wholesale for $280 or less, so for that you need a motherboard, hard drive (there goes your $80 for those two items) profit, power cables, controller, assembly, shipping, motion control stuff?. It's a tight fit to put it kindly.
And what would be the point again? Getting blown away in 2-3 years when MS and Sony are ready? Or do you think this would just have Wii control again? If it did, why would any third parties support it when they dont support the Wii, and when you're talking 3-5 year development cycles, you know MS and Sony are going to have better hardware anyway by the time your game is done?
Basically you need to look at any Wii successor as a total system imo. Are you proposing it be a simple normal console with no motion control (obviously not)? If not, what gimmick are you proposing?
Not to say there isn't one out there I havent thought of. I didn't see the 3DS coming.