I think the next Apple TV will probably have an ARM CPU and Power VR GPU in it, running on the iPhone OS. Maybe a 1.5Ghz-ish Cortex A9, with a 400Mhz-ish SGX545 and 512MB of RAM. Apple could open it up for game development, and make a controller attachment for the iPod Touch (they have a patent for this) and have them be used like a controller for games on the ATV. Hopefully it'll also have a coaxial/HDMI input with a 500GB drive to act as a DVR for cable/satellite content as well.