That's why I'm rooting for Hillary to cling to her spot and not be indicted until after Trump crushes her in a landslide....the longer it takes to have to replace her, the less tie they have to get any kind of campaign rolling.
It could get weird if the dems dump hillary and then don't choose Sanders. hillary's supporters (like some on our side for a certain candidate) are SO invested and in denial that one has to question how strongly they'll support a fill in. If they pull that, Sanders supporters will justifiably be livid with rage about the rigged system.