I'll bet we get a large number of abstentions at the top of the ballot. I abstained from a presidential choice back in 2004, finding about Obama and McCain flawed in ways such that I really could not support either one.
Right now pretty sure I'll abstain unless I can find it in myself to hold my nose and vote for Hillary. But I doubt it.
By "abstain" I assume you mean you just won't cast a vote in that part of the ballot, but will vote for other candidates. I wonder what the outcome would be if voters could choose "None of the above" for each category.
