If/when Sanders manages to do well in the primaries, it's looking like the number of Democratic Party superdelegates could easily tip numbers back in Clinton's favor. There are 4,764 overall delegate votes, according to Wikipedia, including 718 superdelegate votes (about 15% of the total). I've been pretty dismissive of the endorsement race, but I had initially forgotten that governors and U.S. representatives and senators are all superdelegates, in addition to a bunch of Democratic Party leadership at the state and national levels.
It looks well over half of the superdelegates currently intend to vote for Clinton, which makes it considerably more difficult for Sanders to gain enough committed delegates through the primary process. Superdelegates can change their mind at any time, and about 50 shifted from Clinton to Obama in 2008 when it became clear that Obama would win. Obama was already ahead in the superdelegate count at that time, though. Let's just hope the primary battle swings decisively toward one candidate.
Here are Wikipedia's pages on the '08 and '16 superdelegate counts:
https://en.wikipedia.org/wiki/List_of_D ... ates,_2008
https://en.wikipedia.org/wiki/List_of_D ... ates,_2016
(the main count there dates back to mid-November)