The headline of a Wall Street Journal editorial tells the tale:

Biden Wins, but Sanders Persuades

The editors continued:

Joe Biden spent decades opposed to taxpayer funding of abortion, until last summer when he revised his values to fit the times.
…
Medicare for All registers 55% support to 33% oppose in Florida; 61% to 32% in Illinois; and 58% to 34% in Arizona. … Only 37% want a restoration of what Mr. Biden sometimes calls “our administration.”

The editors concluded with this:

It’s Joe Biden’s moment, but his agenda…show[s] how fast the party is moving in Bernie Sanders’s direction.

Stated differently, it’ll be Senator Bernie Sanders (I, VT) running for President on the Progressive-Democratic Party ticket; he’ll just be using Joe Biden’s mouth to say the words.