Just for the record, the GB was "disfellowshipped" by Jehovah on November 10, 1992. Fred Franz died on December 23, 1992, just 2 days before the second coming. So they are supposed to be CLUELESS and a barren wasteland with no green grass of truth at this time. This applies to their understanding of the "generation" and what to expect during this generation to fulfill Jesus' words. So here are the "errors" corrected, so that ultimately some don't think Jesus' words failed just because the WTS has the wrong understanding.
1. First of all the "end of the system of things" mentioned in Matthew 24 is not Armageddon or the end of the world. He was talking to Jews under gentile rule and that was the "system of things" they looked forward to ending. They understood when the gentile times ended and the new, independent nation of of Israel was reestablished (i.e. the rebudding of the fig tree) that Christ would be "near at the doors." So there was an association between the "end of the system of things" and the second coming. The second coming would arrive very shortly after the end of the system of things, that is, the end of the gentile times. So the WTS does not understand the "end of the system of things" is not Armageddon.
2. The WTS thinks the "great tribulation" is also connected with Armageddon. But it is not. The "end of the system of things" indeed follows on the heels of the "great tribulation" but this great tribulation is clearly a local event, not global. And women without small children could escape it by fleeing into the mountains. This "great tribulation" was a major "sign" though leading up to the second coming. It is clear in the Bible that it is completely over before the "sign of the son of man" appears, indicating the messiah had been born. "Immediately after the tribulation of those days..." Again, the WTS is clueless! How can they explain Armageddon comes first and is over before Jesus arrives? They can't. They don't understand. Thus the "great tribulation" that Matthew is discussing was actually the HOLOCAUST and WWII.
3. The "generation" reference that Jesus is thus noting is saying that from the first sign, which is a world war until the appearance of the "sign of the son of man" there would just be one generation. Included in this generation would be the "great tribulation" where 2/3rds of the Jews would be exterminated (Zech 13:8) but also it would see the reestablishment of the State of Israel within that generation as well as the birth of the messiah after which the "sign of the son of man" would begin to appear to the selected anointed ones ("eagles"). The "end" occurred thus in 1947. The new State of Israel occurred in the Spring of 1948. This was an indication that Christ was "near at the doors." The messiah was born in early 1950. So a "generation" can be understood in its most direct reference, that is a generation like that generation in Moses' day after the Exodus of just 40 years. That would be the primary reference in the mind of Jews to a "generation": 40 years. And that concept of the 40-year generation indeed was fulfilled with "all these things" occurring within that generation, including the preaching of the "good news before the end comes" in 1947.
So in conclusion the WTS' problems figuring out the generation and the great tribulation and the end of the system of things is their own problem complicated by their being in spiritual darkness and unable to see. It is not a problem for Jesus and the Bible, however, in being fulfilled. There is no need to try to find a means to stretch that generation past 40 years from 1914-1994 in order to fulfill that. And indeed, the "sign of the son of man" has been appearing to the anointed "eagles" so this is real.
The WTS will never understand the "last generation" because they don't understand the "great tribulation" (Holocaust) or the "end of the system of things" (end of gentile times in 1947, not Armageddon). They are clueless and totally in spiritual darkness and only speak from a barren spiritual wasteland. In the meantime, the truth is known to the "eagles", the JIOR, who are the faithful anointed ones and the "wise virgins."