I am contemplating what the real implications would be if this really was forthcoming edict from the GB:
1) The R+F would be thrilled about having the onerous task of door-to-door removed. However, what about pioneers? Gilead Missionaries? etc? These people would be completely screwed and literally have NOTHING left to do with their lives without their magazine peddling "careers". Imagine the fall-out from these people. These are for the most part, uneducated, unskilled boobs who would have no recourse beyond burger flipping should the "preaching" work cease.
2) The long term result , inevitably, is the complete bleed out of membership, as the older ones die, no new recruits being brought in, and most JW kids not staying in beyond the teen years.
3) They would effectively be giving themselves a very dangerous "time-limit" by "testing" jehoobie in this manner. People die and new people are born. Whats the max age before a child reaches the ability to intellectually absorb the watchtower "message"? 12-14? All of these "new" people would effectively never have a chance to hear about the borg, which is a complete contradiction of their claim that Matt 24 has been fulfilled.
4) After setting up this open-ended "time limit" for armageddon, each passing year would lead to greater and greater resentment among the R+F, this resentment is now even amplified because the GB had gone so far as to boldly claim they had fulfilled all these prophecies....NOW its all Jehoobies fault......