There’s an ugly irony here: the supporters of Mr. Biden will almost certainly vote for Mr. Sanders if he is nominated. The supporters of Mr. Sanders might not return the favor.

This is false. 12% of Bernie primary voters switched to Trump in 2016, but 15% of Hillary voters switched to McCain in 2008. I see no evidence that so-called ‘centrists’ actually have more party loyalty than leftists when it comes down to it. Many of them would much prefer a Trump than Sanders presidency because their class interests would remain unchallenged.