Why is everyone so sure Harris will run? I think she would realize how unpopular she is and just retire. She’s older than she looks—will be 64 by e day 2028—so there’s no shame in stepping out of the public eye.
If Biden wins this year: If Harris runs she will start as the frontrunner, but would probably still lose the primary and the general if she gets there. If she's the incumbent by that point, then she'll win the primary. I'm going to assume she won't run though. Whitmer and Newsom are the clear favorites at this point (I honestly think I'd vote for Newsom in this lol). Wes Moore and Andy Beshear would do well if they run. Warnock and Roy Cooper would be hyped early but fizzle out.
If Biden loses: pretty much the same as above except Harris is even less likely to run.
I think she's almost certainly going to run if they win in November, so I think she's in the appropriate column for now. If she and Joe lose, I'd probably bump her down to a 50/50 chance. Losing didn't dissuade Mike Pence from running.
EDIT: Added Jon Ossoff and Adam Schiff to the unlikely list and knocked Fetterman down to 50/50.