I thoroughly dislike both US parties, so don't really have a horse in the Trump/Biden race.
Near the end of the Hillary/Trump race, pollsters consistently said there was no "path to victory" for Trump in the electoral college. In fact, just looking at Trump's campaign itinerary for the last 2 weeks spelled out the path to victory. Hiding in plain site, but pollsters and commentators were too lazy to see it.
Trump voters are distrustful of pollsters and media. They tend to be undercounted.
This election, like the last, is likely to be decided by 2-3 million key voters. 38-40 states are pretty predictable leaving 10-12 battleground states. Even in those battleground states, most registered DEM/REP are already known. That leaves 250,000 or so independents in the 10-12 battleground states who decide the winner.
Biden's choice for VP is critical. A lot of the women on his short list may not play well to the independent battleground voters. The VP choice can lose this election because lots of voters believe Biden may not be healthy enough to complete even 1 term.
Trump seems likely to run a "law and order" campaign. Why run against Biden/VP when he can run against Antifa and rioters?
Democrats have a very beatable opponent, if they don't screw up. If they go too extreme/progressive, that will be great for fundraising and enthusiasm, but it will lose the election.