I don't see this happening. The current GB members didn't invent this religion. They bought into this stuff just like the rest of us did. Therefore, I think we'll eventually see the WT undergo changes involving a complete reinvention of their eschatology. It would be easier for the GB to implement those kinds of changes because it doesn't have to involve any admission of error. They could explain it away in their mind by saying that Jehovah allowed them to be mistaken for decades so that people could come to worship him and now Jehovah has seen it fit to provide his people with a clearer understanding of the truth, etc.
Ding ding ding. I agree 100%. I think the GB would be smartest to disavow any particular "end is near" eschatology, and instead invoke an "end is coming... but we have NO IDEA WHEN OR HOW SOON". This provides the disconnect between a specific date or immediate reward. Their focus would turn, as motivation, to a lifetime of loyalty that leads to some FUTURE resurrection reward... an intangible item that is hard to "disprove", since you have to die and be resurrected to know it was true. As with hellfire, a powerful motivating force in some religions, the fear of what will happen in your afterlife can be a powerful carrot that leads for a lifetime.
This is a great thread.