I agree with Nick Pope ( the Ministry of Defense official who was assigned to investigate British UFO sightings and became a strong believer thereby). He feels that there will never be a 'big D' but only lots of gradual 'd's'. I believe this is already happening:
http://www.realufos.net/2009/06/major-steps-so-far-for-ufo-disclosure.html
If the US sinks as an economic empire, I fully expect to see entire nations accept the reality of ET's while the US continues in denial - largely due to the influence of fundamentalist Christians here. These days even the Vatican seems a hair's width away from espousing belief That We Are Not Alone ( and actually that change surprized me). If the Vatican does have its own intelligence apparatus, they may know a lot more than they are saying.
Eventually, even the Watchtower may be forced to respond to the controversy. There was a poster named "Prominent Bethelite" years back who claimed that the Society even had a secret paper prepared for a Big D, should that ever happen.
Such a development would reveal the real moral character of the Watchtower. Would they warn the "faithful" that such is completely a plot by demons - knowing that it would likely be a mere stopgap measure? Would they accept the finality of it all instead?
I wonder if ordinary Witnesses would collapse into a sort of frightened mass denial, while younger Witnesses accept the new reality that we are just a backwater planet in an immense universe. As it is, many Witnesses presently sustain themselves with tight controls over their own thoughts to avoid the terror that they may have wasted their lives on an illusion.
We are living in interesting times, indeed.
metatron