The Watchtower's breath of life is dependent on the last days that started in 1914.
You can’t change 1914 without a DEATH BLOW TO THE ENTIRE ORGANIZATION.
I find that Ex-JW's are more aware of this kind of doctrinal issue than are the typical R&F JW. A much younger JW friend mentioned to my elderly JW mom about the "nearness" of The End being espoused by the Borg. Mom went out on a limb and asked her if she thinks it is any nearer than it was in 1975 or 1941? Of course, this young woman was not even born in 1975 and has no effing idea what all was said, etc. She of course thought all that 1975 stuff was "apostate" exaggeration.
FACT IS, JW'S DO NOT KNOW WHAT THEY BELIEVE. Ex-JW's have done A LOT more investigating into the Borg than has any JW that I know -- otherwise they would also be an EX-JW.