I think Trump is good for 25 to 35% of the Republican vote and 10 to 20% of the Democrat vote across the board. He gets 90% of the active and veteran military. Some Sanders supporters will go to Trump as well.

Then add in a bunch of people and groups that generally do not vote because they generally never have a candidate which represents their interests. Your seeing this now in the poll numbers of new voters.

If Hillary has not been criminally charged, before the nomination he will destroy her head to head or in a three way.

Trump takes the middle of America not the extreem right or left but a big chunk of the middle. He gets that middle no matter what.