If she doesn't have a VP before the election, which would be possible because of ballot issues. Then Congress would have to approve any appointment, very unlikely leaving Johnson next in line. Senate would still be unable to remove her, thanks to the 66 vote threshold so we avoid President Johnson.
At least in the world where democrats win I think the White House and Congress go hand in hand. The Senate has been a bit of a longshot this whole time but who knows.
I’ve been playing around with Don getting the White House but dems getting a super majority in both houses, us spending the next year and a half or so in impeachment trials for him and scotus