3. There isn’t much separating top from bottom here.
One of the problems that Republicans had in 2016 was that the incentives for candidates to drop out simply weren’t there, and this was a direct consequence of the size of the field. Most of the 2020 minor candidates have been involved in races where they have come from behind or had a substantial surge in the polls. Right now none of them are more than three points out of fifth place in Iowa, none is more than nine points out of fourth place in New Hampshire, none is more than five points out of fourth place in Nevada, and none is more than seven points out of fourth place in South Carolina.
To be clear, I’m saying that finishing fifth, fourth, fourth and fourth would get a candidate the nomination. But because the Democratic race is sequential, scoring at this level in a few early races probably extends a candidate’s lifespan, and all of these candidates are within striking distance of such a showing.
Moreover, since the eighth- and ninth-place candidates will likely be dropping out, that will free up a significant number of voters. Again, where those voters go is sort of up for grabs; it seems like they should gravitate to the major candidates, but their status as voters for minor candidates suggests that there are things about the major candidates they already dislike.