Well, looking back at the thread (almost a year?), all of us said some pretty embarrassingly-imprescient or uninformed things. For me the worst was, while I was on the right track concerning recent rule changes for GOP primaries and bound delegates, I mistakenly thought that the 400+ bonus delegates would all be unbound until the National Convention.

At any rate, given the preponderance of proportional delegates and the concentration of winner-takes-all bindings on March 15, I speculate that:

1. We are in fact down to just Rubio, Cruz, and Trump after the first shots in Iowa. No one else can realistically expect to meet the upcoming thresholds. Indeed, if Carson holds out he will only sap votes from Trump.

2. Trump's last chance for a Republican path would be March 15 (Super Tuesday). After that, he is either set (on paper), or he has to give up (on paper).

3. Depending on March 1 (Super Duper Tuesday) performances and his supporters' reactions, Trump will indeed back down - mediocre performance leads to anemia by mid-March - or he will threaten to schismatize the party with an attempted coup or an outright break (most likely in the case that he maintains consistent proportions and is in second place but 50-100 delegates behind the leader).

4. Unless it turns out that Trumpians are really resilient to setbacks, Carson promptly drops out and gets the VP nod, and Rubio and Cruz vacillate and cannibalize each other's delegates, Donald Rhetoric Duck has blown all his steam and is now a rhetorical lame duck. That's it, people, no need to give the Trump candidacy any more thought.