In other words the Society is saying that Jesus was referring to the entire Christian church as the "generation" that would not pass away.
When I was growing up and had my weekly bible study with my mom, I learned that "this generation" had two fulfilments. That when Jesus was talking to his apostles about them being the part of "this generation that would not pass away until all these things occur", he referred to the time passing until the destruction of Jerusalem in the year 70 AD.
I also learned that this prophesy had a second fulfilment (they always have, haven't they?). And this second fulfilment started in 1914 and ending with the big A.
In paragraph 10, it's being referred to "the contemporaneous generation of unbelieving Jews" vs. "the modern-day fulfillment".
And paragraph 15 has this footnote:
The time period during which "this generation" lives seems to correspond to the period covered by the first vision in the book of Revelation. (Rev. 1:10-3:22) This feature of the Lord's day extends from 1914 until the last of the faithful anointed ones dies and is resurrected.—See Revelation—Its Grand Climax At Hand! page 24, paragraph 4.
So they are still talking about "this generation" passing from 1914, but it's crazy enough as it is
kifoy