I think I understand the expression, "Invisible Growth." It's what I have seen in the past several years as the number of JWs (as published by JWs themselves) continues to climb from a little over 6 million. Now I see the WTS is claiming a membership of 7 million. Yet all the anecdotal evidence I see (in the United States) is that KH attendance is way off, the number of congregations is not growing, and the attendance at dub meetings is about the same as it was 10-15 years ago. A lot of people have left. They've been replaced mostly by dub kids growing up and getting baptized.
If it weren't for the impact of immigration of Hispanics to the U.S., there would be negative growth in California and several other western states.In this, the WTS is a lot like cigarette companies: Having suffered dramatic sales decreases in the western world, they have simply grown the market in the Third World. When the third-world population wises up, they'll have nowhere to go.