" Unless it completely rebuilds itself the Watchtower will die of boredom." I think this is so very true.
Also relevance to people's lives is an issue, once a JW starts to ease off from the Mouse in a Wheel life that the Org demands of its adherents, she or he realises that the Org has little relevance to their day to day life, couple that with the incredible boredom of the Meetings, what is needed at that point is some sort of trigger, and they will be off.
Another thing that is even more of a problem for those who want to keep the org going is that the young ones have in the main seen through it, and the older ones are dying off, and yet the Org now has no real way to attract new recruits.