^ Neither of those things is a good idea.
Anyway, Gillibrand dropping makes sense, as she was down to basically zero. Here are the current RCP polling average standings:
Williamson, De Blasio, Ryan, Bullock, Steyer, Bennett, Delaney and Sestak should go pretty much immediately.
Klobuchar is in the debates so she probably stays but she shouldn't, so she goes next, along with Gabbard if she can't get into the October debate. Booker, Castro and O'Rourke probably next. Mayor Pete and Harris have been fading but they've got enough that they'll probably stick it out.