B: 3. (Less printed literature in other languages) Reason: There is less need of printed literature generally, and more and more of the world's population that can read, read English.
C: 3 (Less printed literature in English) or possibly 4. The traditional "colportage" business model was weakened in 1990 and has since been broken by the internet. Printed literature has turned from being the primary income earner for WBT$, to just a drain on the business.
D: 3 (Less Bethel's than today)
I think the biggest threat is not membership. It is the finances. WBT$ now has to rely more on member donations and bequests than ever before. I am sure that they will survive, but they will have to make changes. I predict less emphasis on field service and more closed cult behaviour.
Witness carts may be a smart move, because their use hides less emphasis on field service. The fact that carts achieve very little is irrelevant.
If they are smart, they will water down the discouragement of higher education, and go to greater lenghts to retain members.
Looking further into the future (beyond 10 years), they will have the following problems:- the "immenent Armageddon" card will lose more credibility as time goes by;- the lucky guess of 1914 will seem less impressive as it will be just another date in history;- recruiting will become more difficult in wealther countries, as JW's only seem to be able to recruit fellow Christians, and the percentage of the population that believe in God in such countries is on a steady decline.