I think if Biden ran in 2016 you basically get one of three options - he squeezes Hillary out of the race and Sanders registers as a footnote in American political history now that the bogeyman isn't the presumptive nominee, Hillary stays in and you get a drawn-out brawl between the two over what would basically amount to differences in personality and whether a woman should get the nomination, or (this is the least likeliest) Hillary drops out and the small-P progressives that backed her simply because it time a woman got the nomination back Sanders against Creepy Joe Biden, Sanders once again does well with young voters, and you get a 2016-esque primary result.Americans, correct me if I'm wrong, but I get the feeling that Biden became a 'plausible' president very soon after Trump won simply because he didn't run in 2016 and so worked as a "he coulda won" figure. If he'd actually run for the candidacy, he'd be squeezed out by Clinton and Sanders and What If Biden Was President would be a tongue-in-cheek AH thing that isn't taken too seriously.
I do need to reread their PM Johnson stuff now we've actually got him.
Biden's always been a plausible candidate, but there was a certain edge of "he's ran three times before 2020 and fucked up every single time, so he'll probably fuck up again" to people's predictions - I certainly remember saying multiple times that he would flame out before the primaries, and he won the nomination with incredible ease.