I am one who thinks a collapse will never happen, although nothing would give me more satisfaction.
You have made some very good points. At the very least, Watchtower's days of healthy growth are over with. What growth there is seems to come primarily from children of JWs being baptised, and outsiders coming in who are from 3rd world countries where the Watchtower message would have great appeal and there is a lack of available information about the organization's past history.
In several years there won't be much growth left to draw on from inside the organization unless they start baptising children, and as the internet and other information media become more available in the underdevelopped countries that market will lessen too.
However, Watchtower is crafty. It has always been able to spin itself into success. Let's hope the lack of good leadership, coupled with abundant information regarding the beliefs and history of the WTS, will cause the organization to run out of good spinning ideas, and considerable weakness in the armor becomes apparent.