I kind of doubt they have any concerns about the ones that are leaving. Most were not likely contributing anything for some time. WT is more concerned about losing contributing members, vs losing hanger-on's that were (if anything) just a drain on resources.
We know of a young couple who were awakened to TTATT who gradually went from PIMO to POMO. As long as their regular continuing monthly contribution was made via the website, no one noticed their "fade". When they canceled their long time contribution, the elders were immediately calling to attempt a shepherding call.