In my own case I viewed the watchtower as a can of half rotted fish - I wasn't about to try to separate the rotten part from the good. I threw the whole damn thing out. But I'm sure these subcultures won't bust up the organization. There have been dissenters from the beginning.
I think the threat of shunning is the only thing that's keeping the JWs together. Whether people believe the doctrine or not, many are unwilling to risk losing their families, so they remain silent. And the greatest threat to the society now is probably the internet, where people can quietly do their own research.
W