I wonder if it would be a good idea to automate this to an extent? If a moderator isn't active in a magazine for a specified amount of time, they're given a 30 day notice that they're about to lose moderator access. If they don't respond, they're removed as a moderator. If no moderator is present on the magazine, you allow applications for users to become a new moderator. That could be admin approved or opened to the community for a vote. If no one applies and the magazine is truly dead, either appoint an admin as moderator or maybe just auto delete the magazine.