Err? Todays computers are already 400% more powerful than PS3 and the max vote is 100%. The next gen will not be as powerful as todays PC hardware or the console will be sold at $700 with a huge loss a la PS3. But we should expect 3 times as powerful and not 5 times like PCs are.
Remember these consoles is supposed to last for a while, so anything less than that and i wouldn't bother tbh, considering Xbox 360 and PS3 can already handle most PC games in sub HD.
Also todays PCs while they are very powerful they are limited by the engines which are designed for current gen consoles. So even if say PS4 is only twice as powerful as PS3, we should see graphical improvements across the board a few years from now, even for Wii U.







