Just as reassurance, mind - i took a quick trip to the bottom of the /f/ index, and the last thread there was started at about the same time (which is when this iteration of GC came online), but had its last post in September 2015.

So the definition of "soon" with regards to disappearance is probably quite loose. In fact there's no way of telling, at this time, whether ANY thread has yet been deleted. There's nowhere near enough traffic or enough individual threads for it to have become strictly necessary yet.