Here are the betting odds average by RCP for the 2020 democratic nominee: https://www.realclearpolitics.com/elections/betting_odds/democratic_2020_nomination/

There's been nearly a 10 point shift over roughly the last 4 weeks away from Joe Biden. Surprisingly enough, the points swing favor towards Hillary Clinton. She has over a 10% chance at the nominee according to an average of betting markets this late into the primary process with every democratic candidate conceding to Biden.

Are democrats actually considering swapping out Joe Biden for another candidate? Current polling shows him up in multiple swing states by 3-4 points but this is with hardly any negative media coverage and Biden not making many public speaking appearances.