The WTS will continue to be what it is: A legalistic religion that is constantly adding rules on top of rules. A religion like that has two possible endings:
- It will literally strangle itself very slowly over time, refusing to make any significant changes.
- It will suddenly explode and loose a very large number of members by making significant changes, then start growing again with a fresh group of converts (as they did after 1914 failed).
I'm inclined to think the WTS will follow path #1.
The WTS or a version of it will continue to exist for a very long time, however it will never achieve a growth rate like it did in the past simply because it is resistant to significant changes.
Right now its Achilles hill is its refusal to accept legal responsibility for the actions of its members. So long as it refuses to legally acknowledge that Jehover's Witnesses are agents of the WTS, it will be doomed to sticking to the failed donation arrangement, which is draining its financial assets.
An example of this is the way the WTS does not have Jehover's Witnesses go in the ministry work with name badges. Using name badges would be a clear legal acknowledgment that the individual JW is working for the WTS and would open the WTS to legal and financial liability to any screw-up the individual JW might get himself involved in. Right now when a JW is sued, the WTS denies any association with the JW and says that the person was acting on his own. This is how the WTS is currently beating the child molestation cases and other liability law suits.
Another example of this is the way the WTS is stubbornly sticking to the "donation arrangement". If the WTS were to start selling their literature they would have to charge sales tax. In order to do this they would be forced to legally define JWs are employees. (Barns and Nobel cannot sell books using non-employees and neither can the WTS.)
The simple fact that the WTS is so adamant against accepting legal responsibility for the actions of their people tells me that they are currently dodging an enormous amount of liability that would otherwise drain their financial assets more quickly than their failed "donation arrangement".
In the end, the WTS will continue to use the "donation arrangement" until it finally shrinks to a sustainable size and an empty shell of its former self. Yes, it will continue to exist for a long time, but at a scale that is nothing like it currently exists.