He's not a politician. He knows business. He tells it like it is.
If you don't think he is Presidential caliber watch him eviscerate the left's best example of a President. At about 6:50 in the video, after Clinton makes a political move to insert populist humor, Cain overcomes Clinton's BS and you can see on his face that he has met his challenge and Cain gains the intellectual advantage.
My initial choice for his administration would be:
Sarah Palin for VP
Paul Ryan for Treasury
John Bolton for State
Patraeus for Defense
Guiliani for Justice, Homeland Security or FBI