If the plausible candidates right now are Biden, Warren, Sanders, Buttigieg, Klobuchar, and Bloomberg, I would maybe consider Bloomberg weaker than Warren but that's it.
Her resume is not better than Biden's where I'm sitting. Biden sees her Senate, with longer tenure, and raises Veep.
Given the polling trends, I see Bernie surging in Iowa, probably 3 to Biden's South Carolina going into the rest of the states. What a disaster. I dunno if Biden can beat Trump, but Bernie sure can't, and I don't see Biden scaring the sh!t out of moderates in Arizona, Colorado, New Mexico, Maine, Michigan, Minnesota, North Carolina, and Iowa.
The highlight of this entire scenario will be the Senate easily having the votes to repeal the ACA, and Obama saying "I told you so" (hopefully on Joe Rogan Exqueerience) and the far left screeching on social media sure to follow.