When i read The op I had some thoughts. According to Watchtower, at least until I left:
#1 Babylon the Great is "The WORLD Empire of False Religion". Of course this would include Judaism, Hinduism and the rest of the Asian religions, Islam, And EVERY religion in the entire world, Christian or otherwise. EVERY religious belief OTHER than WATCHTOWER.
# 2 Babylon the Great FELL in 1919. The belief was regardless of weather or not the numbers grew or diminished, It fell because the BELIEFS held by the various religions NO LONGER HAD ANY HOLD on JEHOVAH'S PEOPLE. In that sense alone they ALL fell.
The "RIVERS DRYING UP", was the sign that B.theG. would soon be DESTROYED .
Falling was the past, DESTROYED was in the FUTURE.
WT loved to say that religions are drying up because people aren't as zealous as they were in the past. Remember, this is primarily a US religion. They disregarded their OWN interpretation of B. the G. by ignoring the zeal of Islamists and other non-Christian religions. They simply wanted to point only to things that could indicate that the GT and the Destruction would be SOON.
Of course, this whole post is how WT uses Semantics. WT splits hairs in order to wiggle out of their many false predictions and interpretations. ONLY when the passage of time reveals their beliefs to be false, do they get "New Light".
Apparently, fewer JWs, especially the under 50s, pay attention to details given by WT. After all, most who did...already left.