I would simply avoid all the talk of cost of particular components and ask "What do Microsoft or Sony gain by releasing a system that is 10 times as powerful as the current generation consoles for a cost that is greater than $600 per unit that they don't gain by releasing a system that is 4 times as powerful as the current generation consoles for a cost of under $400 per unit?"
I could be wrong but I suspect a system that was 4 times as powerful, output at 720p@30fps, and sold for $300 would be more popular and profitable than the more powerful alternative.