My suspicion (and it's only that, the Dems and I don't talk) is that the Dems are grooming a youngish, energetic, smooth talking, flim-flammer with excellent optics that will take Biden's place shortly before the election (but in time for ballots), perhaps after any notion of a debate.
I could be wrong, but that's my prediction; and, maybe we GOPers should plan for the Dem candidate bait-and-switch.
Dwayne "The Rock" Johnson for President
JMO, YMMV