Biden is the October surprise. But how does he get on the ballot in 50 states? Does he get by with no debates? Can he avoid saying anything stupid before Election Day? Will the GOP take this to court or is this not another hill not to die on?
Ballot access is for the party, and literally NOT the candidate. Voters vote for and choose presidential electors. The candidate names appear only as a crutch to facilitate completing a ballot.
And even after the general election, the party can change who the electors will name, in the ballots they send to Congress. This would be done if a candidate became unavailable.