There was an earlier thread, IIRC if O gets tossed before Dec 15 (EC vote) then the DNC gets to choose a replacement; if after Dec15 it’s up to congress to do it.
I don’t remember seeing anything in the Constitution that allows a political party to exchange a candidate after a general election. The State ELECTORS could choose to vote for another candidate, but then McCain could file suit as an injured party. I don’t think this is going to end as nicely as some people think. I also think if the SCOTUS chooses to disregard a very clear portion of the Constitution, especially one that is easily remedied (show the certificate) then how can you selectively enforce ANY law?
Further, this could be done “in camera” The only people that would actually see the certificate would be the Justices. There is no need for the public to see the actual certificate, but the Justices could determine eligibility and rule accordingly.