I'd say it's the internet and social media that is having the biggest impact on the Watchtower. They are able to use it themselves and because of that, they have lost much of the magical mystique they once had over people by becoming too common place because of over exposure. Also there is a good chance that any JW who uses the internet, could at any time, run across information that could get the ball rolling in terms of opening their eyes.
It sort of reminds me of the situation that Donald Trump is in. Certain groups are afraid of what he could "undo" in terms of strides that have been made toward "gay rights" "racial and gender equality" and "environmental" issues to name a few.
Because of the internet and peoples ability to spread the word quickly it will be very difficult if not impossible for him to sneak anything by anyone or try to take things that were hard fought for, away from anyone. He has made himself too much of a commoner via all the media exposure he's had and his regular tweets. It's so easy now for the public to know what's going on to and spread the word.
Gone are the days when the masses blindly accept what those in positions of authority, tell them to do. Anyone (other than born-ins) have no one to blame but themselves if they don't look at the JW teachings from all sides, before becoming involved with them.