This is other side of the coin with Biden winning the nomination that I have been addressing for a while.
The Democrat Party is simply too wide to realistically encompass everyone who the label, if they even do accept the label. If Bernie won, then he would alienate the moderates. But since it appears Biden will win, he will alienate the extremists. The Dems cannot have it both ways.
The real question is whether Bernie, in losing the Democrat nomination, will choose to run as an independent. That effectively fracture the Left and hand the victory to Donald Trump on a silver platter.