I have never been a Jehovah Witness but was involved in a similar controlling religion. I have maintained an interest in the major cults such as JW's, Mormons and even minor players like Scientology (I think that many people were like me in honestly believing that surrendering any critical thinking to their cult will bring them to God).
I believe that the Jehovah Witnesses have been in decline in North America for about ten years or so, based on the decline that I have seen in my former controlling group (I don't believe any numbers that the WT produces). The Watch Tower organization reminds me of the former East Germany before it collapsed (not that I expect the WT to suddenly dissolve). East Germany tottered along for years with its internal problems papered over for the most part. It provided a bland and secure environment for its citizens who in turn believed or pretended to believe the propaganda that the state produced (common joke was that we pretend to work and they pretend to pay us). East Germany slowly weakened but hung on with support from Russia which was hardly in better condition. When the system collapsed, the end came quickly. I suspect that the Watch Tower will soon experience a critical tipping point after which it will transform itself into a smaller and ever diminishing organization. I fear that the remainder may become even more fanatical as they try to adjust to the new reality and the ever changing WT dogma.