I'm not sure whether anyone is arguing they are thriving. Where once they prepared for expansion by building halls, now they sell them. Everything they do signals to me they expect contraction.
i think an inflection point has been reached. They hit their zenith and are headed down. The signals of decline are leading indicators of what is about to occur with a decline in membership.
It'll not be a dramatic collapse though. If it were for example, half the size (in the West) in 25 years that is not a collapse to me, but it is a pretty sizable decline nonetheless. Even that level of decline seems rather optimistic to me - i could see there being a third of the current membership gone in that timescale perhaps with those left being mostly quite aged - but still, I think it will feel like a shadow of itself.
The internet is making such a difference. It feels like where once JW's were confident and proactive, now they are defensive, reactive. The ex-jw community on the other hand are growing in their confidence and are increasingly empowered to speak out through social media to communicate the damaging realities of the JW religion.