“... would never get any Reagan Democrats crossing over, where Trump would”
Hillary got twice as many votes as Trump in his own state about a million to Trump’s five hundred thousand. Doesn’t look like there are enough crossover votes to make a difference. Trump will still lose NY to Clinton in November.
So, for that matter, will any Republican.
The 40% of dem primary voters who voted for Sanders could be Trump voters in the general. Besides that, keep in mind the Dem voters were in-place for months, and couldn’t switch to vote for Trump. Some would probably go to Trump in the general, a choice they didn’t have in the primary. Because the Democratic Party in NY is so much larger than Republicans, it could easily be a significant number.
NY is a closed Primary but open General Election. Democrats and Independents were not ALLOWED to vote for Trump last night, but they will be allowed in November.
Reagan won NY with cross over votes and it wasn’t even his home state.