This is my thought. I could imagine Biden announcing that Obama was coming in to play a very key role in his administration and that might give him a boost. That while technically the buck stops with Biden still, that Obama is very close to contribute.
This would sidestep the “annointed one” problem, avoid skipping the primary, and while it’s short of a new candidate, it gets a very popular person near the presidency who couldn’t have been the candidate.
I couldn’t imagine them starting from scratch at this point, couldn’t imagine who they would pick that people would already resonate with.
Sunday school is not a public institution, which is why it gets a pass. Similarly private schools are free to do this all week long.
I think even this supreme Court would rule the correct way. I wouldn’t be surprised if it were even unanimous, but at worst I’d expect the 6/3 split with Thomas, Goraych, and Alito. There’s only so far they can go when the Constitution was very blatantly clear on this matter.