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.
if you lean on everyone hard enough and successfully enough, you can get people all-in for Harris as Biden's heir at a convention. (do I bet everything I've got on that as a possibility? I do not.)