Despite the lackluster records of JW number growth in the past 6 years, I believe that their numbers will start to swell again and remain high for at least another 10 years Here is why.
The Society is becoming more and more business like in its approach (especially after last year's re-org) on how to maintain and increase growth. The WTS, like any corporation when it becomes acutely aware of stagnation, begins to formulate a number of new techniques in order to bolster its sagging membership or sales. This could include, TV ads (I believe Intuit39 mentioned something to that effect), radio, newspaper and magazine ads and direct mailings. Video productions, specialized newsletters, even perhaps dedicated cable tv channel.
The Society is a huge publishing empire with deep pockets, and although it has experimented in other medias before, it will now have to throw its weight behind them.
Despite the negative JW info found on the internet, close to 150 million, half the population of the US do not have online access. The newly devised marketing campaigns will mainly attract seniors and low income single parent families and immigrants. The attraction of seniors alone will have a major positive impact on the WTS checkbook, as these seniors are more likely to make large donations and bequeath large portions of their estates to the Society. In fact, is is those seniors that will fund most of the expenses associated with Kingdom Halls and expansion.
The demographic makeup of JWs is going to change and there is going to be less emphassis on the door-to-door approach as seniors and single parents are not best suited for such work.
By the time the newly recruited seniors pass on and the low income single parent and immigrants get online, the Society will have accumulated a good second wind enough to propell it for a decade or two.
Incidentally, the influx of new seniors may well boost the number of "annointed" partakers.