if a website like this existed in 1975, there would be not a few of its participants confidently predicting the complete demise of the watchtower. spoken about enough, it would have sounded much more a certainty than current speculation about 'tides turning.'
I don't see the WBTS going down anytime in my lifetime. They may dip in membership, but there are always news ones ready to sign up. At my old hall the membership has stayed the same for years and years, but I'd say in the past 5 years there are at least 50% new members.