Every religion has a significant proportion of ambivalent or marginal members, it is in no way unique to JWs. Sociologists have sometimes discussed this ‘free rider problem’ in relation to religious groups. However some argue that free riders are actually essential to the overall well-being of a religious community because they perform a number of crucial functions: such as presenting a variety of ways of being a JW to outsiders and potential converts, being used as examples not to follow by the leadership, and free riders often convert into zealous members themselves, if their circumstances change, or go back and forth in their commitment levels, so they provide a pool from which hardcore support can be sustained over time.
I don’t think the legal pressure on Watchtower to change their disfellowshipping practice is all that great. We’ll see how it plays out in Norway, but even then it’s only one small country, and even if other countries follow, Watchtower can describe it as discrimination. I wish Watchtower would change, but disfellowshipping seems to work for Watchtower so why would they change it?
Nondenominational churches are often churches that have split from denominations. Many churches are disaffiliating from the Methodists in the United States at the moment over the gay marriage issue. In Scotland a congregation split from the Church of Scotland over the same issue, calling itself the ‘Tron Church’. Conservative members from other congregations joined them, producing a measure of ‘growth’ for their small group. But considering these members came from a number of congregations, and the church going population as a whole is going down, I don’t think it's all that accurate to describe it as growth. It’s more like a temporary cluster for conservatives to gather around amidst overall decline across all churches.