Someone pointed out that it might be handy to compare current teaching on the generations, properly cited. I'm going to quote two sources; the Watchtower magazine of April 2010 and "Reasoning from the Scriptures" published 1989. A Witness to remain in good standing must follow current teachings.
From the Reasoning book:
Definition: The Bible uses the expression “last days” to refer to the concluding time period leading up to a divinely appointed execution that marks the end of a system of things. The Jewish system with its worship built around the temple in Jerusalem experienced its last days from 33 to 70 C.E. What occurred then was pictorial of what would be experienced in a greatly intensified way and on a global scale at a time when all nations would be facing the execution of judgment decreed by God. The present wicked system of things, which extends worldwide, entered its last days in 1914, and some of the generation alive then will also be on hand to witness its complete end in the “great tribulation.” - Reasoning from the Scriptures (1989), "Last Days", first paragraph
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Luke 21:31, 32: “When you see these things occurring, know that the kingdom of God is near [that is, the time when it will destroy the present wicked world and itself take full charge of earth’s affairs]. Truly I say to you, This generation will by no means pass away until all things occur.” (The “generation” that was alive at the beginning of fulfillment of the sign in 1914 is now well along in years. The time remaining must be very short. World conditions give every indication that this is the case.) Reasoning from the Scriptures (1989), "Last Days", under the heading, "To what do all these events of the 'last days' point?"
From 2010 Watchtowers:
14 What does this explanation mean to us? Although we cannot measure the exact length of "this generation," we do well to keep in mind several things about the word "generation": It usually refers to people of varying ages whose lives overlap during a particular time period; it is not excessively long; and it has an end. (Ex. 1:6) How, then, are we to understand Jesus? words about "this generation"? He evidently meant that the lives of the anointed who were on hand when the sign began to become evident in 1914 would overlap with the lives of other anointed ones who would see the start of the great tribulation. That generation had a beginning, and it surely will have an end. The fulfillment of the various features of the sign clearly indicate that the tribulation must be near. By maintaining your sense of urgency and keeping on the watch, you show that you are keeping up with advancing light and following the leadings of holy spirit. Mark 13:37." Watchtower 2010 Apr 15 p.10 Holy Spirit?s Role in the Outworking of Jehovah's Purpose
"John Barr made clear that the gathering would not continue indefinitely. He referred to Matthew 24:34, which says: "This generation will by no means pass away until all these things occur." He twice read the comment: "Jesus evidently meant that the lives of the anointed ones who were on hand when the sign began to be evident in 1914 would overlap with the lives of the other anointed ones who would see the start of the great tribulation." We do not know the exact length of "this generation," but it includes these two groups whose lives overlap. Even though the anointed vary in age, those in the two groups constituting the generation are contemporaries during the part of the last days. How comforting it is to know that the younger anointed contemporaries of those older anointed ones who discerned the sign when it became evident beginning in 1914 will not die off before the great tribulation starts!"
""The sons of the kingdom" eagerly await their heavenly reward, but all of us must remain faithful, shining brightly to the end. What a privilege we have to see the collecting of the "wheat" in our time." Watchtower 2010 Jun 15 p.5
I am quoting excerpts from WT articles as cited from a larger article at: http://www.jwfacts.com/watchtower/generation.php
The hundredth anniversary of the start of World War 1 is swiftly approaching. The time indeed has not been short. It is quite obvious that the WTS is fiddling with the generational teaching to try and hang on to that 1914 date. The result is confusion. How could a Witness in good standing ever hope to keep this straight?