If you haven’t done it, read the whole article. It raises the issue at different times in the process. If someone cannot serve after the election but before the Electoral College casts it votes, the electors can choose whom they want. It wouldn’t necessarily be Joe Biden (if Obama is found to be Kenyan). It could be................................................................................HILLARY!
Sorry, that is correct. Before the electors vote, it is whomever they want. They are, at that point, representing their party/states. My guess is your right, it would not be Biden ;)
After they vote, it would, constitutionally, have to be Biden.