They are gone. Forget them. But luckily, they're only about 20% of the population. What I'm hanging my hat on in this election are the vast swath of voters who voted for Trump in 2016 (or who didn't vote at all because they didn't like either one) but have now seen the error of their ways. And trust me when I tell you, I've talked to A LOT of these people.
I get the appeal of 2016 Trump. He appealed to a large group of voters looking for a fresh face with an "outsider's" mentality who would come in and shake things up. I understand that appeal because I was (and still am) one of those people looking for someone to come in do things "out of the box." It's the reason why Ross Perot appealed to so many people back in 1992 (the difference being, Perot's voters weren't enough to put him over the top, whereas Trump's voters combined with his cult following to create a group big enough to win). Unlike many of them, though, I did enough research and critical thinking to realize that Trump was NOT that person. What I'm saying is that I think that a lot of the people who wanted an "outsider" who would come in and "clean up the swamp" now realize that Trump isn't that guy too, and will turn against him.
I also know a lot of people (more people than I can believe, actually, including members of my own family) who just plain didn't vote at all, mainly because they "didn't like either one of them." I think the vast majority of the "sit this one out" voters have now seen the error of their ways and will re-enter the fray in 2020. And between the two groups I mentioned, I would bet you're talking about a significant vote swing. That's why I truly believe that as long as the election is LEGITIMATE (and I have zero faith that it will be), we win this one handily. It's the Russian hacking that will be the downfall of this country, and it's literally something we as common folks can do nothing about when the people tasked with protecting us..........won't.