Everywhere you can read about Famitsu, Big Boss, the old man, Kojima Productions NEXT and teaser site, Metal Gear Raiden, etc. But nobody seems to figure it out.
But think logic. Picture of Big Boss? Hideo speaks of the old man. It's not Big Boss, it's Solid Snake! Look at his military hat. No Foxhound logo but something completely different. Check out the link for more 'answers'.