There are many symptoms of decrease and I guess it is going to get even slower.
1. New ones are mainly foreign language speakers. At English conventions many foreigners get baptised. An influx of Polish JWs has brought not only new members but many active JWs came over. 10 years ago there was 0 Polish circuits, now 3 or 4.
2. Many English congs especially rural ones are getting old. I know at least 5 where average age is over 60 and they have 50% at their meetings for obvious reasons.
3. Preaching pattern is plain stupid. They go out in mornings for an hour or so knocking on empty places. Btw Mormons in my town do their job at night and they do catch people in. Even local Witnesses can see it.
4. 3 years ago at the elders school, a teacher from the branch did maths: 80% not at homes (to be positive, it can be around 90%), average 4 people per house but just 1, the same, in the morning (others at work or school). It makes - JW reach just 3-5% of population in.
I must say that foreign JW are much more zealous and friendly in general. Sorry if I upset anybody.