I guess, there are 2 things tha could wreak some havoc in the WTS religion:
1) Going mainstream (less control, more moral freedom, less shunning, diluting fundamentalist doctrines, and basically more members) - this may take dozens of years, although there are some syndroms already
2) Then, with the standards loosened up, dissent within the borg would have to take place. One or more charismatic, consistent, and cunning leaders on the inside of the system with a considerable support of the common folk would do the trick. From my Polish perspective I would say a WTS Lech Walesa (rather than Ronald Reagan) would be necessary :).
I mean, this is how most major religions split up. Oppression from the outside tends to unite religious groups and gives them the illusion of being persecuted by the evil forces. On the other hand outside forces could exert pressure on the WTS to change some of its policies and go mainstream, thus contributing to the process.
As it is the WTS is too small and too oppressive and thus easy to control.Even if half of the Governing Body rebelled, they'd get df-ed by the stronger, thicker-skinned half and quickly replaced by a bunch of newly annointed freaks. So it's all rather wishful thinking for now.
Pole of the former Communist Block