Sparky1 is correct. Thank you Prologos for expressing your thoughts, I did some research as well and came up with the following.
Their current interpretation of 'this generation' is so whacky that it would be better to focus on that rather than their timeline (GT, rest of Anointed dying and Armageddon).
With their previous interpretation of 'this generation' they have said the following. Also, they hardly acknowledge that it was their own interpretation but coming from Jesus.
W 51 7/1
The length of time is indicated by him when he said, “Truly I say to you that this generation will by no means pass away until all these things occur.” (Matt. 24:34, NW) The actual meaning of these words is, beyond question, that which takes a “generation” in the ordinary sense, as at Mark 8:12 and Acts 13:36, or for those who are living at the given period
W 61 4/15
The foretold events having begun A.D. 1914, the generation of mankind that is still alive from that year is the generation meant by Jesus Christ
W62 3/1
The generation that sees the start of these foretold events, Jesus showed, would live to see the end.
However, I do appreciate why you are coming up with your current thoughts. That is probably because in their past interpretation they made it clear that 'this generation' included those that would pass away at Armageddon but also those that would survive through Armageddon.
There is a lengthy discussion through a QFR W 78 10/1 that includes this idea.
Jesus said “this generation will by no means pass away until all these things occur.” Which generation is this, and how long is it?
When Jesus’ apostles asked for a “sign” about his presence and the conclusion of the system of things, he gave his famous prophecy about coming wars, famines, earthquakes and the preaching of the good news of the Kingdom before the end. (Matt. 24, 25; Mark 13; Luke 21) He also said: “Truly I say to you that this generation will by no means pass away until all these things occur.”—Matt. 24:34.
Based on the Bible and its fulfillment in history, Jehovah’s Witnesses have often pointed out that Christ’s prophecy was to have two applications: First, between 33 C.E. and the destruction of Jerusalem in 70 C.E.; second, a larger fulfillment in this “time of the end” since 1914 C.E.
However, some Bible commentators have failed to appreciate the dual aspect of this prophecy. So they have held that by the term “generation” Jesus meant a race or people, such as the Jewish people or the class of wicked humans existing through the centuries. They might even refer to 1 Peter 2:9, which, in the Authorized Version, speaks of the anointed Christian congregation as “a chosen generation.” However, Bible scholars now recognize that the Greek word in 1 Peter 2:9 should be rendered “race” and is different from the word rendered “generation” in Matthew 24:34.
Jesus was not referring to a race of people over the centuries or just to Christians. He was first of all referring to his listeners and other Jews at that time. An indication of this is the fact that earlier that day, when condemning the Jewish religious leaders, Jesus spoke of their murdering the prophets and said: “All these things will come upon this generation.” (Matt. 23:36) These words came true on the contemporary generation when in 70 C.E. the Jews in Jerusalem faced its fiery destruction. (Luke 3:16, 17) That also marked the ‘conclusion of the Jewish system of things’ in the first fulfillment of Christ’s prophecy.
This helps us to understand “generation” in Matthew 24:34. In common English usage today “generation” might be used for (1) all persons who were born and who live about the same time, or (2) the average span between the birth of parents and that of their children, usually 20 to 30 years. Which did Jesus mean? Obviously not the latter, for in its first application the “generation” ran from 33 C.E. until 70 C.E., or at least 37 years.
Also, it is evident that by the word “generation” Jesus did not mean just the Jewish children born in 33 C.E. Luke relates that after being asked by the Pharisees when the kingdom was coming, Jesus told his disciples: “[The Son of man] must undergo many sufferings and be rejected by this generation.” (Luke 17:20-25) That rejection certainly was not by newborn babies. Likewise, the way things worked out shows that the “generation” he spoke of in Matthew 24:34 included his listeners and others who could discern the fulfillment of his words from 33 C.E. onward until Jerusalem’s destruction.
Thus, when it comes to the application in our time, the “generation” logically would not apply to babies born during World War I. It applies to Christ’s followers and others who were able to observe that war and the other things that have occurred in fulfillment of Jesus’ composite “sign.” Some of such persons “will by no means pass away until” all of what Christ prophesied occurs, including the end of the present wicked system.
Jesus did not encourage his followers to try to calculate the exact length of this “generation.” (Ps. 90:10) Instead of trying to figure how many more years, at the maximum, there may be until the end, Christians should remember Jesus’ warning: “Keep on the watch . . . because at an hour that you do not think to be it, the Son of man is coming.”—Matt. 24:42-44.
Now they have created a new problem. If 'this generation' means that the overlapping group of anointed will pass away during the GT but before Armageddon then the GT could last for decades (or even Centuries).
I hadn't picked up on this point before until you brought this topic up Prologos. This in effect means that 'this generation' teaching has no bearing on when Armageddon is to take place, unless it can be determined how long the Great Tribulation will last.
If we look at their discussion in the 2014 Watchtower headed with the title "Let your kingdom come - but when?" it now becomes obvious that they are only talking about 'this generation' indicating a time during the GT, not Armageddon itself.
Under the sub heading of This Generation they say
THIS GENERATION WILL NOT PASS AWAY
14-16. What is a third reason for believing that God’s Kingdom will “come” soon?
14 There is yet a third reason for confidence. What has developed among God’s people points to the nearness of the end. For example, prior to the establishment of God’s Kingdom in heaven, a group of faithful anointed ones were actively serving God. When some of their expectations about what would happen in 1914 did not come about, what did they do? Most of them proved their integrity under trials and persecution and kept right on serving Jehovah. Over the years, most—if not all—of those anointed ones have faithfully completed their earthly course.
15 In his detailed prophecy about the conclusion of this system of things, Jesus said: “This generation will by no means pass away until all these things happen.” (Read Matthew 24:33-35.) We understand that in mentioning “this generation,” Jesus was referring to two groups of anointed Christians. The first group was on hand in 1914, and they readily discerned the sign of Christ’s presence in that year. Those who made up this group were not merely alive in 1914, but they were spirit-anointed as sons of God in or before that year.—Rom. 8:14-17.
16 The second group included in “this generation” are anointed contemporaries of the first group. They were not simply alive during the lifetime of those in the first group, but they were anointed with holy spirit during the time that those of the first group were still on earth. Thus, not every anointed person today is included in “this generation” of whom Jesus spoke. Today, those in this second group are themselves advancing in years. Yet, Jesus’ words at Matthew 24:34 give us confidence that at least some of “this generation will by no means pass away” before seeing the start of the great tribulation. This should add to our conviction that little time remains before the King of God’s Kingdom acts to destroy the wicked and usher in a righteous new world.—2 Pet. 3:13.