...train a machine to recognize a spin down in academic debates...
Off the top of my head, having a program track a Google Alerts feed on the topic (with filtering via Yahoo Pipes if Alerts gives too many false positives) and let you know when it's gone a certain amount of time without getting any input seems like it would be a reasonable first approximation of that.
For miscellaneous discussions and remarks not suitable for top-level posts even in the Discussion section, let alone in Main.
(Naturally, if a discussion gets too unwieldy, celebrate by turning it into a top-level post, just like in the good old days.)