I don’t see any scenario where she would ‘just’ resign unless health got into the issues.
Then you come to the Senate approving Newsom for the VP job. There’s probably ten Democrats in the bunch who really don’t see Newsom as a better replacement. He’s also a straight male-model looking guy...which is a no-go for the party.
Adding to this scenario...Biden won’t go quietly into the night. He intends to be there to the bitter end, even if he’s marginally competent.
I also will point out...if the House goes to the GOP...there will be a Hunter Biden investigation, and the money business will lead back to Joe. Senate won’t impeach Joe, but there’s enough financial issues (tax evasion) that you could bankrupt Joe Biden.
Adding to this scenario...JILL won’t let Biden go quietly into the night. She intends to be there to the bitter end, even if it kills Joe (in her mind only a big loss because it gets her out of the White House sooner?).