wow, what a great thread and responses. I have to pitch in, too.
I think the subtle social schisms already brewing under the surface will grow, that is, there will be a definite sector of JWs, mostly in NA, Europe and other developed secular lands, that will simply be going along b/c of family and social ties, who will either recgonize the BS and not take it seriously or who will consciously refuse to examine it critically so they can maintain the status quo. This group, which will increase, will have the effect of neutralizing the evangelizing spirit, softening the rhetoric and generally moving toward a good works/charity/family-based theology as opposed to rampant end-times. The GB will be forced to respond with a "kinder, gentler" face or lose a heavy swathe of publishers (who might only be getting in 3 or 4 hours and that maybe in the form of visiting the elderly in nursing homes, etc.) Pioneer hours will be reduced to 50/mos., softening on the higher education stance, etc. AT the same time, in third world countries and amongst immigrant groups, there will continue to be high growth and an emphasis on end-times ideology. I think in 20 years time, English speaking JWs will be a significant minority--yet still the source of most donations, hence the need to soften the hard core dogma, as I mentioned.
I have family members who recently came back from a trip to Patterson NY and were bubbling over with all the good experiences JWs were having in the territory around there, how the angels were directing the work, how the spirit is so dynamic and exciting with all kinds of growth happening.