And who would it even be? I'm sure we could all come up with a short list of candidates we'd prefer, but I doubt there's a single candidate who could both satisfy enough Democrats to unify the party *and* get a national campaign up to speed at this late hour (especially without the advantage of incumbency).
Democrats spent the first part of this year going through the best available process for deciding whether to replace Biden as their nominee. It's called "the primaries". Only three people bothered to run against him, one of whom explicitly ran on Biden's age. None of them polled higher than 15% and Democratic voters in all 50 states overwhelmingly chose Biden to be the nominee.
Poet, music geek, politics junkie, baseball fan (no particular team), dad-joke composer, anti-fascist, kitty 'n' doggy petter. https://spoutible.com/Steve_Carll