I do think that many JWs are "main-streaming" it. In other words they go to meetings, out in service, etc. but really dont care. Remember its a social club also, friends, family, something to do. I know many JWs who watch violent movies, play violent video games, have a little too much to drink, stay home from meetings on occasion for reason, etc., etc. It will take a tremendous, earth shattering event such as a GB member being caught on video with a man or a hooker and evidence that the others tried to cover it up to shake some people up. Even then many will not even pay attention.
Its a pyschological hold that being a part of a congregation holds over you that causes the... whats the term cognative dissonance? I would guess that in a given congregation 25-30% or more dont care about the religion anymore. However each of those people would never reveal their doubts because of fear of retribution and being cut off from the rest of the group to shut you up. Its sad because if all these people in every cong around the world would reveal themselves then we would see a big change. Fear prevents it from happening.