Remember the Sega 32x which coupled two Hitachi SH1 32-bit CPU at 23 MHz with Genesis? Should that ideology work for current gen consoles? PS4 and Xbox 720 are coming out in 2011 with DirectX 11-like GFX.
I believe In 2010, either Xbox 360 and PS3 need an hardware addon with another R600 or G84 GPU core and extra 128 MB GDDR3.With this enhancement, Sony can expand to Open GL 3.0 Graphics and it will be a lot cheaper than purchasing a PS4 to do DirectX 11-like. Otherwise you can make them really cheap and have them as a pass thru device with only the new GPU chip and no memory. It'll use all USB ports to get adiquet speed. We don't need them anyways.
Both of these would likely be less expensive and at the same time actually look next generation anyways.