Loyalty, devotion, hardcore, willing to lose jobs to attend Friday of the District Convention. These were the witnesses who came into the truth or were born into it some 30-60 years ago. They could reason from the scriptures and hold their own at the doors.
Today, I see a large mass of witnesses who have been in some 10-15 years who really don't know much about their own faith, could not explain 1914, are unwilling to lose jobs and sleep over attending meetings and assemblies and live double lives. They would rather leave a tract at a not-at-home than engage in real doctrinal arguments.
Their children and the JW youth in general are internet and media savvy, willing to question rather than accept what they are told.
Are you sure the WT can keep going forever when it's older, loyal members slowly die out?