Here is a reference to a Twitter discussion on the National Popular Vote. If the Dems were really serious about this they would hold their party primary on one designated day nation wide, winner gets the nomination, but why quit there?
Show us you're open to diversity. Let anyone on the ballot who can raise some minimum amount of money toward their election, say $10 million, put that much money into a pot, and again, winner take all.
Even better: Let anyone vote. Citizen or not, D or R. Allow on-line voting from other countries. Who cares. The winner will most likely be selected in advance by the party central committee who will coincidentally be in charge of counting the votes. Someone with experience in vote counting should be in charge, say Rham Emmanuel. Unless he decides to run as well in which case Robert Mueller gets the job with the proviso that he announce the winner within 2 days of primary day and any ballots arriving after the announcement will be immediately incinerated. No foot dragging. Likewise for all other ballots. Electronically cast ballots will be given the Bleach Bit treatment and the devices recording them will be shredded.
A couple of campaign managers will die of natural causes, and Hillary will get another shot at Trump. Sound fair?