it depends on what the national Dems do, the people who control the campaign money. the Democratic right might do what they did with McGovern in '72 and essentially prefer the Republican on the grounds that he won't disrupt the current party system. if this happened, Sanders would likely lose close to Dukakis '88.
if the national Dems did try honestly to get Sanders elected president, I think he would be much more Kerry '04 than Dukakis '88 against Jeb Bush, and might win against a Cruz or Rand Paul. here's a vs Bush type map. Pennsylvania could well go the other way.
