Crafters who do not gain any XP for a period of .. I think it is 3 months? .. will fall off the active crafter list, regardless of whether or not they keep crafting items that are trivial to them in that trade. At least, that is how the list currently functions, which is your question as I interpret it. They will still appear on the all-time crafters list, assuming they have achieved a spot on that list as well.
