I am waiting for the point when the Republicans, both party and voter realises they threw away an entire election on Donald Trump.
But really when it comes down to it the Sanders supporters are going to decide this election, they are typically Millenials and Millenials are the largest voting block currently (18-35) and if they decide to vote against Trump or not vote for Hilary will decide who gets to run the Govt for the next 4-8 years. That of course is barring any kind of October Surprise where the candidates skeletons come tumbling out of the closet and the party doesn't have time to spin it and recover to win it.
It is an important election because the next president will get to chose 2 supreme court nominees which will decide if the court leans Republican or Democrat. Unlike the president they sit a life term and will basically decide important laws like gay marraige, legalization of weed, bathroom laws, abortion, ect. Republicans know that if they lose this one they lose the supreme court for at least 20 years and may never recover it.