OK, let’s say that tomorrow, it is revealed by a reputable source that Joseph Biden was born on a slow boat to China (Liberian registry, natch) to a Vietnamese hooker and Ulli Gulli, the Swedish spy. He got a fake green card in a box of crackerjacks and just never left. There is no way in Hell he has any claim on American citizenship. Does he stay on the ticket? Does he stay on long enough for the Electors to elect him and then resign? Could Obama appoint another Veep, cross Biden off the Electors’ ballots and pencil in :: mumble ::'s name?
(Hey, it’s no less plausible than Obama not really being a citizen.)