Probably EVERYONE else thought of this long ago, but I, being an "independent thunker" thunk of it just a coupla weeks ago.
We all know that since the year zero (on the FredFranzian calendar) the WTB&TS has defied archaeology and insisted that Jerusalem was destroyed in 607 BCE, even though the physical evidence shows that 587 BCE is a more likely date. In fact, the book "The Gentile Times Reconsidered: Have Jehovah's Witnesses Been Wrong All Along About 607 BCE?" by Carl Olof Jonsson and Rud Persson made this conversation public.
It is a difference of 20 years. If the WTB&TS drops their adherence to 607 BCE, then the "Bible-based arithmetic" moves the "critical" year 1914 forward 20 years, to 1934, which is exactly what the rumor mills are saying will happen. Now we know why the date 1934 will gain prominence: the WTB&TS will announce "new light" declaring that crackpot Freddy Franz was wrong and the archeologists were right after all.
But you knew that...