No, the Witnesses are a very diverse group. True, as the WT as mentioned, in most cases those disfellowshipped are the younger between the ages 15-35. However, the rate of tose returning is quite high, over 80%. A recent study by Kephart and Zellner reports that most young people who live the Witnesses return. And new ones coming are usually younger. In fact, meeting attendance in most of the world is basically by the younger generation, which is the group doing the most preaching. In fact, in some European countries, one of the main reaons that there is a lower number of publishers is due to the older brothers, not the younger ones. European congregations have a greater number of older brothers, those aged 75 and above. These are all considered to be faithful brothers and sisters. But the since the WT society counts the brothers that are only actively preaching, the growing number of "inactive" elderly brothers do not appear in the number of active publishers. I put inactive in quotes since many of the elderly brothers attend the KH meetings or have the meeting taped so that can listen to them at home.