Since it's the leaders' clan, it is their decision of whether to close the clan due to inactivity/quitting of just the him/her self, and/or other leaders/founders. If they wish to close the clan because of this, then so be it. That's their decision since they created the clan, but if a group of the clan want to try to attempt to "remake" the clan under different leadership like we've seen happen, that is also another option. I think there could be leadership depth under the main founders/leaders, but the founders/leaders who quit runescape don't want to see their clan crumble if they do decide to pass it on, and make a bad name for the clan.