What will the Watchtower look like in 30 years?
My predictions are more like 15 years ahead, further predictions are pure fantasy since society in general might change with unknown effects on the JWs.
Yes, I know JWs are isolated from the world in general but I predict very bad times for the world and that might actually help the Witnesses in increasing their numbers. Fundamentalist religions love misery.
Will there still be a Governing Body?
Always. The lust for power will always be there. And what would the alternative be, a non-hierarchical structure?
Will they finally drop 1914?
No, but as someone previously said here they will take the chronological voodoo out of it. They'll probably "forget" the "generation" issue. In any case, Adventists are doing well regardless of how irrelevant their date 1844 is for their general faith.
Will the blood doctrine finally be dropped?
It will probably be a conscience matter, more so than today. Also, by 2030 viable blood substitutes might be in use.
Will disfellowshipping be dropped?
Maybe underemphasized but I'm sure it will still be there for extreme cases.
Will there still be Circuit Overseers, Elders, Pioneers?
Their hierarchy will stay in tact although it may undergo some changes (whatever happened to District Overseers?). They are an authoritarian religion and I believe they will always have a top to bottom command structure.
Will there still be Judicial Committees?
That's the same as asking the question on disfellowshipping being dropped. If disfellowshippings are maintained to any degree you will need a judicial committee.
Will they still have conventions 3 times a year?
I'm sure they'll still have conventions though they may be weekend or single day conventions. Pardon the ignorant question but how long are they now?
How many meetings will they have a week?
Maybe two days like now though the weeknight meeting attendance might be reduce in hours and somewhat "optional".
Will they still go door to door preaching?
That is up in the air. They all hate field service and the cart witnessing is a more preferable option so that might take over a lot of their field service.
With the carts they don't get into people's private space. They don't need to be eloquent. At most they simply hand out leaflets.
Will they drop the name; “Watchtower Bible and Tract Society?”
Why should they? They have their bible and they will still have tracts to hand out.
How many members will they have worldwide?
If I'm not mistaken aren't they somewhat increasing in non Western nations? If global situations go from bad to worse there will always be people needing something to have faith in.
Also, we can't assume the Internet will affect them outside of English speaking nations. I'm not sure but I don't believe there are many ex-JW websites of our caliber in most of the languages that many JWs speak.