I think the whole 120 Years Moses thing that recently came out was supposed to ease the fears of the average JW that they *MIGHT* have been wrong about the whole end of the world thing.
Remember when they said that someone had to be an adult when 1914 happened... then they changed it to a teenager... then a child... then a baby....
Now they are saying that someone, in theory, could live to be 120 years old. This new date range is just another thread for the JWs to graps at.