That's how I see it Ian. I can't understand people on here saying Witnesses are going to be pleased about this. If this happened ten years ago when I was a happy Witness I would have been devastated. The group study is the best meeting of the lot. It has a great atmosphere, encourages people to get to know each other, and I dare say you are right, it allows elders to keep a closer eye on publishers.
Plus what about the older Witnesses who have their group study in the afternoons these days. I think those groups have become quite popular in some congregations, and I know in my congregation many old and infirm ones attend the afternoon book study who very rarely make it to the other meetings. It is their last connection to the "truth" as they get very old. If they take this away from them I think they will lose a lot of ill/older ones altogether.
Practically all the changes in the past 15 years have been to save money, and I suspect this change must be about money somehow too. So that's why I speculate about a knock-on effect from the new schedule reducing the Circuit Overseer's workload. And if the Circuit Overseer's position is taken over by voluntary part-timers then that would surely save the Society a lot of money. The new volunteers could be trained to oversee congregation accounts just as well as paid Circuit Overseers do now. So that need not be a disadvantage.
Mormons already have a system like this I think. They have volunteer bishops who do a lot of work similar to what Circuit Overseers do, except they don't get any money for it.