I agree that that if BHO is found to be not qualified to be POTUS, John McCain will have no claim on the presidency. According to the Constitution, if POTUS is found to be ineligible or incapacitated, the presidency passes to the vice president, or the vice-president-elect. In this case, Joe Biden.
While it is true that BHO has been unable to produce a legitimate birth certificate, is there ANY proof that he was in fact born in a foreign country? As things stand right now, it seems as though the burden of proof is now on US to establish a foreign birth.
However, if you read the XX Amendment, you will find that if the President-ELECT does not qualify (that would be prior to inauguration), then the VP-elect ACTS as president until a president is qualified.