I could certainly get behind the theory that the body of the Sphinx is considerably older than the head, but the idea that the pyramids are 12000 years old is one I have trouble with, partially because they don’t show the rainfall-type erosion that the Sphinx body does, and also carving an existing rock into lion shape isn’t the same as building those three pyramids.
A yardang that’s been resculpted several times doesn’t seem to overturn the history of much of anything IMHO, but I don’t think you’ll ever get an Egyptologist to give an inch on this, having to deal with aliens and stargates and such gets them all twitchy.
That one guy that seemed to be a big proponent of the 12000yo Sphinx has shot down some other Atlantis discoveries (ancient city off the coast of Japan - natural formations says he) but he seems to go off the deep end when around the Sphinx. I only buy about a third of what he says, but that third was enough to make me suspect there is more to the story. Not a highly advanced ancient civilization, however.
Just my 2 cents, based on little more than Discovery Channel shows (so worth slightly less than 2 cents)