I'd say your polls from April 16 were spot on and Sanders was the only one that could beat Trump. There was no election fraud or voter suppression though.
Now most Bernie supporters are split up between Clinton, Stein, Johnson and the ones that plan to write him in and the Dems didn't think it would go this way. I doubt a Bernie supporter would go Trump but so many people are pissed off who knows. I know quite a few 20 somethings who were staunch Bernie supporters who pledged to go Trump because in their eyes "if you can't fix the system, crash it and start from scratch". I don't know how it will go, I just know this country can't keep going on like it has.