"But I have a hunch that there could be a massive exodus from the Organisation. Especially those who know the WT history well..."
The problem is, there aren't very many Witnesses that know the true past of the Organization. Watchtower has been masterful at revising it's history.
I believe this is changing, but not because the 100th anniversary of 1914 in near.
The older generations of Witnesses had no easy access to what the Organization was really teaching prior to 1914, 1925, etc. After each failure there was an exodus of people from the religion, but the Society would later spin that into "Jehovah cleansed his earthly Organization,' resulting in most Witnesses today thinking those who left were 'over-zealous,' or they 'misunderstood' what the Society was teaching, or they were only 'serving for a date,' and needed to be weeded out.
It's changing because the younger generation is tech savvy, and they have easy access to amazing amounts of information via the internet. In spite of strong warnings from the Society not to search for information about Watchtower's past history, many do it, and more will in the future. They are learning the true history of the Organization, as are many of us older ones now, and it will only snow-ball as time passes.
Watchtower is reaching a point where it can no longer cover up it's sins. Will the religion end? They almost never do. Will it eventually decline? Absolutely. It will be interesting to see how much, and how fast. Watchtower's struggle is just beginning.