Two men with cancer in their history? McCain's had two occurrences.
Not a chance.
McCain may hate Bush, but he has no future as a second banana, and knows it.
Hell, McCain would be 70 in 2008, if he lives that long, and have no chance at the Presidency.
What are the chances of any individual in this country becoming President of the United States? Awfully slim, even if you've climbed to the rank of Senator or Governor.
But if you've climbed to the rank of Vice-President, you historically have a one out of three or four chance of eventually becoming President (that's a ball-park estimate, since I haven't bothered to actually add up the numbers). Since World War II, five (Truman, Nixon, Johnson, Ford, and Bush Sr.) out of eleven Presidents were former Vice-Presidents. And Gore came within a few hundred votes of making it six out of eleven.
Those are damn good odds. If McCain still lusts to be President (which is a pretty safe guess), then his best remaining hope by far is to accept the VP slot under Kerry.