The most obvious possibility is AOC. In that case I am sure she'll move even further right and get totally ratfucked by the party regardless. That's the most jokerified option, I think. At the very least, her obvious ratfucking will push many more people to the left like the Bernie campaigns did.
But the worst possibility is some rando Democratic apparatchik we've never heard of like Mayo Pete showing up. They take up all the aesthetics of Bernie's campaigns, they receive the glowing endorsements of Bernie and the squad, but they seemingly refuse to outright promise anything we would call "good", and they suspiciously receive no material push-back whatsoever from the Democratic party establishment other than some clearly bad faith grumblings about how spooky and radical this person is. Win or lose, they completely suck the energy out of leftist movements in the imperial core for a further decade.
The DNC using the pandemic as an excuse to suspend primary elections and just declare a winner in 2020 certainly didn't help either.
But rember, vote and never do literally anything else. Even if last time the people telling you to vote canceled the election because they explicitly said your vote doesn't matter we've picked our horse.