The GOP is not unified but neither is the Democratic Party.
The way the DNC conducted itself [openly favoring Hillary Clinton] angered many people not just Sanders supporters and this, in November, will prove to be a costly mistake.
Democrats were counting on Trump-hate for a November victory but they were wrong. And it's too late for them to change anything now.
There are some who speculate that while we focus on Hillary and Trump, a third party candidate might win the election.
http://wnct.com/2016/06/22/2016-third-part-candidates-could-cost-clinton-or-trump-election/
Doesn't look good for Johnson but if he can get the support of Sanders fans . . .