So imagine the GB have a sudden attack of honesty and realize "crap, this whole thing is lies - we're not god's spokespeople at all !". But then what?
How do you dismantle a religion that has +8 million members in a responsible way? You can't just publish a Watchtower saying "we were wrong" because that would be irresponsible - you need to let people down gently, put people off gradually. Besides, if you announce your sudden lack of belief then there's a good chance you'll be booted and someone else installed as leadership before the WTS in question ever gets into the hands of publishers.
So what do you do? Do you gradually introduce policies to turn the screws to make it less attractive or loosen them to make people less devoted and zealous?
If it was you at the top, how would you dismantle things and how long would it take? A decade? Several decades? Is it even possible?