Nate Silver seems to be saying the writing is on the wall at this point

[Dr. Jack]

21. I think that is the key takeaway from 2016 but people don't realize it yet

I think Hillary Clinton is a good person and would make a good president but fair or not, she has a ton of political baggage. A lot of people don't like her and would never vote for her no matter how bad the Republican candidate is. From a praticle standpoint she was never a good choice as a nominee. It has everything to do with decades of right wing smears and conspiracy theories. A lot of people in 2016 knew Trump would make a terrible president but they also couldn't bring themselves to vote for Clinton. Unfair? Absolutely. But that is reality. That is why Bernie Sanders, at the time a little known independent senator from Vermont (yes I know we all knew who he was in 2016 but most Americans and even Democrats did not) was able to get 45% of the vote and come fairly close to beating her in the primaries. Sure his message appealed to a lot of people but a good amount of his support was probably from "anybody but Clinton" Democrats. And that is why he failed to take off at all in 2020. He was running against much more "electable" Democratic candidates. Suddenly the "anybody but Clinton" voters in the primaries were free to choose, dare I say, better candidates than Sanders.

And I think that is what we are going to see in the general election in a few days. Trump barely won in 2016 because the anti-Hillary sentiment was just a bit stronger in key parts of the country than the anti-Trump sentiment. Take Clinton out of the picture, put in someone who is liked way more with way less baggage, and suddenly Trump can't gain any traction. It's not that Trump was some kind of political genius in 2016 or that he changed the political landscape of the U.S. He simply ran against an extremely weak Democratic nominee which allowed him to barely hold together a winning coalition. Biden is far, far stronger of a candidate than Clinton and that is why Trump has been losing badly this entire time. Just like in the primaries, take away Clinton and suddenly the "fringe" or oddball candidates (sorry Sanders supporters) have virtually no appeal.

There was no great miracle that allowed Trump to win or an untapped electorate that he was smart enough to know about. People knew he was full of shit in 2016 but some figured he was the better of two terrible options. We suddenly have a "good enough" to actually quite greate candidate, and now Trump is down by double digits.