This is true..... but I disagree with your appraisal that voters would not get behind a more progressive democratic nominee. Trump struggles to beat these elites and there's a fair chance he will lose to one of them without securing a second term. This proves that people are, as a whole, dissatisfied with him - excluding his core group of actual supporters who make up less than a third of the nation. The only question is are they more dissatisfied with Trump, or with the prospect of Biden winning and continuing to represent the centrist, establishment agenda? I think if the dems had nominated Sanders, Sanders would have gone on to win. He certainly would have in 2016. Early polling between Trump and Clinton was always close and delivered a slight majority to HRC which actually reflected the popular vote. Early polling before the primaries were over showed Sanders miles in front of Trump. When the dems assured Bernie wouldn't win, most of his voters stayed home and others actually voted for Trump. I don't have much doubt he would have won a few of those rust belt states that ended up making the difference....MI would have been a lock. The Democrats failed to learn their lessons from Hillary's loss. They've pretty much employed the same strategy....trying to convince people to vote against Trump rather than for their candidate.
I have little interest in the election, tbh.....I think Biden would be a disaster too. He's already indicated he wants to increase military spending. If Biden wins it will be a return to the same old military expansionist agenda and no meaningful relief for the working class on a domestic level. If Trump wins, domestic policy nightmare and ever increasing chances of military conflict with China. Either way, the US is looking down the barrel of a long, painful recession, continued conflict in the middle east (the Middle east Peace deal is only a propaganda stunt involving two nations who were always extremely unlikely to engage in any form of conflict with the us and is only inflaming tensions between the Israelis and the Palestinians) ever increasing chance of war on both a domestic and international level.
Whatever happens, the US (and in all likelihood the world) loses.