This election is nothing like 2016
Trump's 2016 coalition is in tatters, as he's lost significant ground with suburban women, seniors, and independents.
In 2016, 33% of Americans believed the country was on the right track. That's good for an outsider. Now that number is down to 20%. That's very bad for someone who is now the ultimate insider.
Many, many people hated Hillary Clinton. Many, many fewer hate Joe Biden.
Turnout was average in 2016. It won't be in 2020.
Turnout was well below average in the "Midwest" States in 2016. It won't be in 2020.
High turnout makes razor-thin victories, like the ones Trump notched in Michigan, Wisconsin, and Pennsylvania in 2016, much less likely.
Third party voting will be way down in 2020 relative to 2016, which likely means fewer Democratic votes spent on protest candidates.
Even if polls are just as inaccurate in 2020 as they were in 2016, Biden will still crush Trump.
There is every reason to believe polls are better this year, particularly since they now correct for education level.
District-level polling was ignored by Team Hillary in 2016, despite red flags. It's not being ignored by Team Biden, and the red flags aren't there.
Trump's polling position today is far worse than it was at this point in 2016. Then, he was an underdog. Now, he's a big underdog.
Everything broke Trump's way in the final weeks of 2016, most obviously James Comey's October Surprise 11 days before the election. This time around, the late breaksbad debate performances, COVID spikes, no stimulus dealwould all appear to be in his opponent's direction.
The Democrats did not take Trump seriously in 2016, and coasted a fair bit, especially at the local level. They are not repeating those errors this year. In particular, the Party's municipal-, county-, and state-level organizing has been extensive, disciplined, and closely integrated with the Biden campaign.
There were few red states in 2016, beyond perhaps Arizona, where Trump needed to play defense. That freed him to play offense in blue states like Michigan. Now, there are at least half a dozen red states where he's got trouble.
In 2016, Trump benefited from being an enigma, onto which people could project optimistic ideas about what kind of president he might be (for example, "maybe he'll appoint good people and then get out of their way, like Eisenhower did"

. There are no longer any illusions about what kind of president he might be.
In 2016, Trump used Antonin Scalia's open Supreme Court seat to get reluctant conservative voters into the tent. This year, he cashed that chip before the election.
https://www.electoral-vote.com/evp2020/Pres/Maps/Oct28.html#item-7