If you're a progressive who supports HRC, you shouldn't WANT the race to be over.
Those of you who are progressive but back HRC are largely driven by the "she's the only one who can win" myth. It's very doubtful that you think she'll actually listen to anyone to her left once she's president. Not if you're honest with yourselves.
But the country is moving left. The country is rejecting corporate dominance of life. The country wants someone who speaks for the outsiders, for the voiceless, for those with nothing.
People want our nominee, whoever it is, to be passionately anti-corporate, to stand up for the 99% against the 1%, and to have a real feeling for those of us(the majority really)left out in the cold in the status quo.
If Bernie were to get out, your candidate would immediately abandon all progressive ideas. She would go back to posing with bleachers full of cops behind her(which would mean she was totally abandoning the criminal justice reform/anti-racism agenda).
You need Bernie's campaign to go on and keep raising the issues, even if your candidate gets nominated in the end.
That's the only way to be sure of anything progressive happening in a HRC presidency at all.