The beauty of the counterfactual in history is that nothing can ever be proven. Nevertheless, they are often instructive.
One that Democrats are going to ponder is whether Bernie Sanders could have won if he had been nominated. I tend to agree with Kevin Drum:
It's obvious that Hillary Clinton's biggest weakness during the election was Emailgate. Republicans successfully took a fairly minor bit of misjudgment and turned it into the world's greatest crime—and kept it alive by shrewdly dribbling out new information regularly. Aided and abetted by Vladimir Putin, Julian Assange, a last-minute assist from James Comey, and a press corps that played along gleefully, this turned into a huge millstone around Clinton's neck that Donald Trump hammered on relentlessly. He also kept up a drumbeat of criticism on TPP, NAFTA, and other economic concerns of the working class.
Plainly Bernie Sanders wouldn't have suffered from either one of these problems. So does that mean he could have beaten Trump?
Sure, maybe. But it probably just means Trump would have attacked him in a different way. Most likely, he would have hammered away at Sanders being a wild-eyed communist. Then Sanders would have lost, and we'd be sitting around wishing we'd nominated Clinton. After all, Trump certainly couldn't have attacked her as a crazed radical. As for that email thing, it was old news. It wouldn't have hurt her much.
In the end, this is unanswerable. For myself, I doubt that Sanders could have beaten Trump. Once he left the cozy confines of the Democratic primaries, he would have been pilloried.
Whatever. Most of my commenters got the President they pined for, so now we'll just have to see how that plays out.