2020 is not 2016.
For one, Biden has been around a long time, but has not faced three decades of Fox News consistently and constantly tearing him down. No, the Fox crowd does not like him... but they don't accuse him of killing people, looking the other way when faced with dire consequences (do I need to say the word "Benghazi" here?), deleting emails, and the raft of bogus charges that Republicans will not let go.
Second, one of the missing elements in 2020 that we suffered with in 2016 was the NRA. Let's not pretend that the NRA isn't eyeball-deep in corruption and money laundering, specifically for the Russians. Remember, we have Paul Ryan and Mitch McConnell on tape discussing how to hide foreign money in political campaigns via the NRA (and it has remained unindicted because Trump holds the pardon pen, among other reasons). With NY State filing charges against the NRA, it has put them under a microscope unlike any other, which has prevented them from funneling huge sums of foreign cash into Republican coffers. To wit: the Trump campaign is broke. And we may owe Letitia James a great thanks for this part of the dismantling of the Trump regime.
Third, while there is a lot of online chicanery, it is not new like it was in 2016. Things were good under Obama, making it a lot easier for Republicans to paint him and Hillary as something they were not; things are not good under Trump, making it hard for Republicans to paint him with anything other than the utter failure he is. Look at all of the crap they've thrown at Biden, from Hunter/Burisma to Sleepy Joe, and it isn't sticking. The shine is off facebook and all social media. We know better. And they are taking minimal steps to prevent the same kind of fake news, not that their steps will make much a difference, but still...
Fourth, at this point in the 2016 campaigns — just under a month out from election day — 17% of voters were undecided and eventually went for Trump (largely thanks to Comey and the FBI bombshell that was the final nail in the campaign to paint Hillary as corrupt and criminal) . Trump was never over 50% of the vote in 2016. Today, we're at 3% undecided. Biden is nationally at about 52% to Trump's 39%. Biden is up in all of the swing states that handed Trump his victory, and those percentages of undecideds (and in about half the states, the yet-to-vote) are equally as low. Those percentages might be a few points higher or lower, but even assuming that Biden's percentage is high and Trump's low, there are too many votes between them for a last-minute bombshell to alter the outcome... unless the bombshell is nuclear. (Literally.)
There is a reason Trump is pining for Hillary's email scandals and continues to gripe about her lack of prosecution (nevermind that there is no evidence of wrongdoing). There is a reason Trump is trying to go full banana republic authoritarian and get Barr to indict Obama, Hillary and Biden with 3 weeks to go. But there is no there there. Barr knows that should he comply with Trump's demands, the House will impeach him in a matter of minutes. No, he won't be removed, but it will mark Barr as the most corrupt AG in the history of the nation.
Finally, Coronavirus and the administration's inept handling of the crisis, culminating in the double-whammy of Trump contracting it himself and Trump cancelling Covid relief talks abruptly, and taking the blame for that failure. At this point, Pelosi had better wake up and smell the victory and stop trying to push through legislation that will only inure to Trump's benefit. We've waited for 4 month for additional relief; we can wait three more weeks. Besides, the Republicans are now prepping for their role as chief antagonists when Biden tries to do anything big, retrieving their fiscal conservative cloth coats from cold storage.
No, it's not a done deal. Trump could still win, and we must act like Biden is down by 10 points and fight like hell. Time to give Joe some more money.