The big iceberg waiting out there for Sanders is the same one that sinks every other exotic candidate, and, trust me, as an atheist Socialist Jew, Bernie's about as exotic as it gets. It's the "I Can't Imagine It" number. It's the percentage of the electorate who are unamenable to persuasion about said candidate, who could not vote for him or her even if an unprecedented number of variables changed. One reason we have senators named Blumenthal and Murphy is because of all the people who wouldn't vote for Linda McMahon if she bought them a new dinette set.