I've just found that my "almost lost cause" has just ignored what I said was its last chance!
My friend has one like that, I'll have to find out what happened to them. He found a new queen at the start of the season who disappeared not long after and for weeks they sat there quite content and probably kept going by the frames of eggs donated to them. They refused to draw queen cells and there was no sign of anything laying. It went on for weeks.