Nice catch, Neon!
And perhaps surprisingly you can find these letters on the WT CD-ROM. Certainly for 2014 anyway. They are there in all their glory in the August 1974 KM. Including:-
(italics theirs)
"... we do know that God's judgment is to be executed within the lifetime of the generation that saw the beginning of the "last days." Jesus Christ said: "This generation will by no means pass away until all these things occur." (Matt. 24:34) Accordingly, the generation of people that witnessed the events of 1914 C.E. is the one that will also see the "great tribulation." Already nearly sixty years have passed. Those persons who were at an age of understanding in 1914 are diminishing in numbers. ..."
Note the "age of understanding" which of course made all of us back then believe that the very last of the generation would have to have been born well before 1914.
If we take age 10 as a minimum "age of understanding" then of the generation that would by "no means pass away" there are only forty verified people alive in the world born on or before Jan 1st 1904* as of February 13th 2016.
If we take age 13 as a minimum then there are only four born on or before Jan 1st 1901*.
*According to wiki's List of verified oldest living people.