With voter participation substantially lower in primaries on Democrats side in 2016, implying such things would only further dampen voter enthusiasm. Talking about lack of voter enthusiasm and participation, assuming Trump will somehow become the eventual GOP nominee, HuffPo writes -

"... buried within the clear victory was a troubling trend for the party front-runner: She is doing a terrible job turning out voters, particularly in the states that will matter most in a November matchup against Donald Trump."

"More people voted for Trump than for Clinton in two states Tuesday night — Missouri and Ohio."

Clinton suspended her campaign on first week of June in 2008. She would have been appalled had Obama asked her to drop out in Mid-March in 2008 before Obama got the majority of delegates needed to secure the nomination.