Here's where I am today:
Reasons to be optimistic:
- Biden is polling much better than Hillary ever did, especially at the end;
- Very few undecided voters left;
- No significant third party candidates that will shave valuable votes off his tally;
- While Biden lacks a great plan B if his plan A (PA) becomes a problem, he has leads in "plan B" states that are not as correlated to each other (AZ, NC, to a lesser extent GA and FL). This is a bit more robust than relying on PA/MI/WI like Hilary did, as they were more prone to common polling errors.
- Pollsters have by and large addressed the 2016 issues regarding educational weighting of white voters, and the 2018 polls were quite accurate in that regard.
Reasons to be pessimistic:
- PA lead is not large enough, and could still be prone to a mid-sized polling error;
- If PA goes for Trump, it's closer to a 50-50 race given the smaller leads in other swing states.
- Unprecedented amount of early voting brings extra uncertainty (we are not sure if polling models handled this particularly well), though this could benefit Biden as well as Trump. But Biden would prefer less uncertainty given his leads.
- Massive disenfranchisement in key states. We saw what happened to GA in 2018. PA remains a huge question mark. And given Republican control of the federal judiciary, there is likely to be a thumb on the scale for Trump (though I can't help wondering if the Republican establishment wouldn't be happy to see him go now that they got their courts - but given the Senatorial races in place it's unlikely).
So all in all, better off than we were 4 years ago, but I would be much more comfortable if the lead in PA was closer to MI or WI.
To keep things in perspective, a Biden landslide in which he wins 400+ electoral votes is probably a bit more likely than a Trump EC win.