If the Democrats do push Biden out, I predict there will be no consensus on a replacement candidate, leading to infighting and, ultimately, a realization that the Democrats have a stable full of flawed candidates that cannot gather national support, particularly in a short time window.
I truly believe they have a lot of extremely strong talent that could gain widespread support over a few years leading to their presidency. But pushing out Biden to take the spot now would kill their careers and hand Trump the presidency.