I took a look at the list of superdelegates and who they were voting for. Bernie Sanders is himself a superdelegate, as is Bill Clinton. Which basically means Hillary and Bernie each get one freebie. Does this usually happen?
All significant Democratic elected officials are superdelegates, and candidates are usually drawn from the ranks of significant elected officials. So yes, this does usually happen. If anything, the unusual part is that Hillary Clinton is not herself a superdelegate.
So Bernie does have a chance.
When did Superdelegates begin? I’m pretty sure it was after 1968, in which case, the only other Democratic candidate I can find who wasn’t a superdelegate at the time was Jimmy Carter. (Walter Mondale was not holding any office in 1984, but former Vice-Presidents are superdelegates; both he and Al Gore are superdelegates in 2016.) I think the only other time since FDRt that the selected candidate would not have been eligible was Adlai Stevenson’s second nomination in 1956.