I do wonder if rather than declaring the Great Tribulation has began, Watchtower will declare they are in the pre-tribulation period (perhaps the Peace and Security cry) and to begin to make preparations. I could imagine this involving selling all Kingdom Halls and going back to a “book study” arrangement meeting in smaller groups in private homes.
Londo, the way I'm slowly beginning to understand this is that once they declare the Great Tribulation is here, they can pull the "oh hey look at that Jesus has given us all the authority" card and then it's
a) the message will change, because they have the authority. Up until that time the message is always supposed to be preach about the King and his Kingdom But if they pull the 'now we have the real authority and such' card then they can change the message at whim.
b) to the bunkers
So it seems that at some point maybe in the relatively near future they're going to need something that shows the flock they have the right to make radical changes. And they'll need those changes in order to either go out with a bang or ... idk, amp it up? But to get those changes they need the followers in a mode of absolute, total compliance.
Maybe I have totally misunderstood it, but that's how it's coming across to me.