Hi Peter,
thanks for writing your thoughts down.
Few quarrels: Nate Silver is a fucking idiot and thinking his model is worth much is a leap of faith in my opinion.
Polling is chaotic but also one of the most reliable ways to assess how well a candidate or party might do; so certainly being behind is pretty bad.
How much should this however impact decision making, given that all of the proposed fantasy-football options to replace the candidate are not clear cut; it is not even clear if any of it would help getting better odds against Trump.
The reality is that there are many layers in US election that make the vast majority of citizens partisan voters; and the race and margins will tighten no matter who is on the ticket.
A weak-seeming candidate like Biden, haunted by the press, might increase voter mobilization in partisans; now their candidate is the underdog agains the elite and the fascist takeover. That grassroots activity of the masses might have a higher chance of changing outcomes on the ground; by making clear what the stakes are to people usually very far checked out of that. In battleground states that activity might be necessary to win; whereas filling in new replacements that will not be able to muster the same level-5-alert activity.
I think for democrats to increase their odds to win the election, the negative partisanship vote has to be cranked up to maximum; and if there was a replacement candidate that could do that, that should be the way to go. So far, all a replacement seems to do is sooth the neuroticism of elites in media, at best making the polls 50:50, but ultimately leading to a sleepwalk towards defeat.
In contrast, Biden staying in, with his traditional coalition of people in the pocket, and alarm turned up to level 5 that he might lose without a democratic uprising, seems to me to give better odds; at least at provoking said democratic uprising.
Either way, I do not think that Americans want to lose their freedom and if the stakes could be made clear to them, I think the odds are better than the current polls predict, no matter who is going to be on that democratic ticket.
The difference between Biden or a possible replacement, in my head, would be negligble rather than critical, if the alarm about losing democracy and their freedom can be tuned up to a 5-alarm in public discourse, which surprisingly it still is not, but almost guaranteedly will be as the elction comes closer.
Anyways, just my 2c.