Personally, I “think” the Speaker (God help us) would be POTUS until another election had been held.
But who knows...
I don't see it that way. The election was held in "good faith" and found proper. The fact of his ineligibility arising after the fact (though questioned during the election process) would not invalidate the election; only his standing.
Biden fulfills the requirements of office. I could see no reason SCOTUS would prevent him from assuming office.
The Constitution does not recognize "tickets", "running mates", or any other such nonsense.
Biden was nominated by the 2008 Democratic National Convention, not by Obama. The Electors for Vice-President of the United States are chosen as the Legislatures of the 50 states direct, and, all 50 states recognize these national nominating conventions as valid for the purpose of chusing Electors.
Mr. iden is absolutely, unquestionably the legal and valid Vice-President of the United States.