The Party of Lenin always maintains Iron Discipline and marches in lockstep. The Bernie supporters will by and large do as they are told and to the extent they vote, the will vote Hillary. They will not be enthusiastic about it, but unenthusiastic votes count too.
They won’t vote many times, they won’t bring dead pets to the polls to vote, and they won’t cover the Bernie bumper sticker with a Hillary one. But they will still vote as they are told.
Or they will stay home.