Rank-and-file democrats who in normal years would be extremely "discomforted" at the thought of voting (R) have been watching how many in the Republican Party reject Mr. Trump's candidacy. This has given many democrats the courage to consider Trump. If establishment republicans are horrified by Trump, how bad could he be? the thinking goes. I firmly believe the crossovers will be huge for Mr. Trump.
Bottom line, Trump will win without NeverTrump republican votes.