They crashed in membership by 75% during the rising Rutherfordian administration. That though, was a series of splinters that did not destroy the hard core membership. Plus, they had a strongman leader that took the miniscule Bible Students Association and transformed them into the militant Jehovah's Witness organization.
Nowadays, JWs don't have any real leadership and I suspect that if something drastic happens most of the governing body will fly off, with a million bucks in their pockets, to some Caribbean mansion.