I think JWs are in serious decline from here on in.
That is a big call, SBF. I hope you are right.
I noticed some of the same things when I skimmed through the Yearbook, such as a huge part of it taken up with Georgia, where growth has virtually stopped. There was also the "spin" Watchtower put on the takeover by Rutherford, which would not sound very convincing to a neutral observer.
Perhaps the single most telling point is the slight decline in congregations in USA. That must hurt the borg more than any decline in any other country.
My guess would be next year will be flat again, with some spectacular growth in 2 or 3 random African countries giving the appearance of overall growth. I think "serious decline" won't be visible for perhaps 5 years or more, as the baby boomers start to die off in larger numbers.