One of Bernie’s real problems is the fact that the establishment wants to run the show. Because of that, they may purposely tank his campaign and he will bring new voters but not have the traditional support. You saw the Repukes do it in 2010 a lot (ta king the campaigns of conservatives who who their heavily contested primaries). A more recent example is Roy Moore.
Hillary still has a big party influence. Hillary isn't a fan of Bernies, but she does like Doomberg, brokered convention here we come.