First of all, "parousia" is poorly translated as "presence." A parousia was like a long procession preceding the actual arrival of a dignitary who arrived at the very end of that procession. So what they were asking Jesus was what would be some of the events or activities that they would see just prior to his second coming? So the "parousia" is what happens just before the arrival, the "erchomai." So if "pre-arrival events" can be understood as "presence" then fine. If not, then "presence" is a poor translation.
What they were really asking was what would be the signs of his "near-arrival." NEAR-ARRIVAL is a better translation of the word "parousia" compared to presence. "Presents" are what you get at Christmastime. Oh, sorry, I got distracted. (oops! -- smile -- it's late, I've been drinking! Let's try that again:) PRESENCE suggests someone has arrived already, doesn't it? You are "present" *after* you actually arrive.
PARA means near to. So this is a reference to what would happen close to the time of his arrival. What would be the events that we'd see just before your arrival or close to your arrival, or alongside your arrival, accompanying your arrival? So they were asking what would be some of the things they would see just prior to his arrival? But also prior to the "end of the system of things?" Clearly, then, the "end of the system of things" was a big event but they understood that that would occur just prior to his arrival.
Therefore the sign of his near-arrival would be those events mentioned, beginning with a world war, which is "nation against nation and kingdom against kingdom." A world war would be the first event of that "last generation." Thus the "parousia" or near-arrival events before his actual arrival would last no more than a generation of 80 years. Since a world war occurred in 1914, his arrival must occur prior to 1994, near the very end of that generation. In the meantime, the "conclusion of the current system of things" would also end.
Now the "system of things" is a reference to the current state of things for the Jews. Thus the specific "system of things" in reference here is synonymous with the "appointed times of the nations" that was to end. So when they thought of the "end of the system of things" they were referencing the end of the appointed times of the nations, which was the current system of things for the Jews. The end of the appointed times of the nations, of course, is also synonymous with the "end of the gentile times." Thus from this context, we know that the "end of the gentile times" was to occur during this 80-year generation between 1914-1994 AD.
But also prior to to the end of the gentile times, the "good news" was to be preached world wide. That is, those woh preached the "good news" would have become an international organization.
Also a major event that was to happen was the "great tribulation" which was to occur prior to the appearance of the "sign of the son of man" which would be seen by the elect in the heavens.
Now, there were to be food shortages and "social unrest" in one place after another. What is customarily translated as "earth quake" from the Greek word seismos, can refer to a storm or tempest or social unrest. So "social unrest" is a more accurate reference of seimos here than "earth quakes" in one place after another or in various places. So besides food shortages and pestilence, easily fulfilled by the Great Depression and the Spanish Influenza, there would be social unrest in the world, obviously leading to a second world war during which the great tribulation would occur.
Now in the Bible, there are two covenants. One with Christians/JWs and one with the natural Jews. When a reference is specific to the Jews, they Jews are called the "greater number" and thus the "lesser number" is a reference to JWs. So when the Bible speaks about the "love of the greater number cooling off" it is speaking about the popularity in the world of the Jews, and thus is a reference to the increase in antisemitism leading up to the "great tribulation" which is actually a reference to the Holocaust during WWII. Thus the "great tribulation" is a reference to WWII. Now that "great tribulation" was supposed to last for 7 years from 1940-1947 after which the Jews would experience the "end of the gentile times" in 1947. But because two-thirds of the Jews were already exterminated by Hitler by late 1944, the "days" of the tribulation were said to be "cut short" or else no flesh (of the Jews) would be saved.
The specific fulfillment of the "conclusion of the system of things," that is, the "end of the gentile times, occurs on November 30, 1947. The preaching of the "good news" occurring prior to this has a general as well as a specific fulfillment. That is, by 1947, JWs had become an international organization and thus had preached the "good news" worldwide by November 30, 1947. "But specifically that year, then president NH Knorr went on an actual around-the-globe speaking tour. Thus that worldwide speaking tour was a specific sign that the "end of the system of things" or the end of the gentile times would happen shortly afterward, and it did! The end of the gentile times did occur on November 30, 1947 with the UN Partition Agreement, and by the Spring of 1948, the State of Israel was established. Both these events, however, were to occur before the "sign of the son of man" would appear in the heavens to the chosen elect and thus also the second coming.
(Oh, yes! I'm so glad to have cleared that up for everyone. You're most welcome!)
Oh wait, one more thing! Specific Bible chronology has to be fulfilled in connection with the "great tribulation" and the "end of the gentile times" 7 years later. These events thus occur in the context of 70 weeks, a 490-year period that would see the end of the gentile times, the second coming, and the "great tribulation." Within the context of these 490 years, the great tribulation occurs after 62 weeks and is referred to as the "cut off." The 70 weeks are divided into 1 week (7 years), 62 weeks (434 years) and 7 weeks (49 years). So after 434 years into the 70 weeks, the great tribulation would occur for 7 years, just before the restoration of the Jews to their homeland for 49 years, the final 49 years of the 70 weeks and also the final 49 years of the covenant. Thus the "covenant" for both Jews and JWs would end in 1996. That's because the 70 weeks occurring during out time begins in 1506 and ends in 1996 based on a countdown of 70-week periods from 36 CE.
4 x 490 = 1960; 1960 + 36 CE = 1996.
The end of 62 weeks or 434 years thus would begin in 1940 (434 + 1506 = 1940). The 7-year tribulation would be from 1940-1947. During this time, two-thirds of the Jews were prophesied to be exterminated during a great tribulation, an event that never happened before nor would happen again. (Zech 13:8) That event was the Holocaust during WWII. But as noted, two-thirds of the Jews were already killed by the end of 1944, so the "days were cut short." That is, WWII ended early in the Spring of 1945. Even so, the "end of the gentile times" did not occur until 1947, when the final 49 years of the 70 weeks would occur, a "week" of 7 years for each day that would see the end of the covenant in 1996.
So it is important to understand that it is not merely seeing these individual events, but those events in connection with the chronology. Of course, the "great tribulation" has to be a one-time event, and that was the Holocaust. Now on retrospect, could anyone think that out of all the signs given approaching the second coming, that the Holocaust wouldn't be one of them? Of course not. It is prominently focused on, only not recognized by most as the "great tribulation," which most people confuse with the "great tribulatoin" that happens to the gentiles just before Armageddon. So there are two great tribulations; one that happens to the Jews or to the "holy ones" during the Holocuast, and one that happens to the gentiles. But again, therefore, the "sign" would have to be a combination of the fulfilled chronology superimposed on the context of these specific events.
Of course, per the Bible, the Holocaust (great tribulation) and the "end of the gentile times" which allows for the State of Israel to be reborn, represented by leaves growing tender on a "fig tree" all happen prior to the second coming and the appearance of the "sign of the son of man" that is seen in the heavens. So the second coming and the appearance of that "sign of the son of man" don't occur until after 1948. Thus the concept of Christ's return and invisible presence at the very beginning of this last generation of 1914-1994 is contradictory to what the Bible teaches. Christ does not actually "arrive" during this generation until after the Holocaust and the State of Israel is set up. The Bible clearly says at 24:29 "Immediately AFTER the tribulation of those days... the sign of the son of man would appear." Further it says that when you see the fig tree (State of Israel) begin to grow tender, then he is "near at the doors," meaning he doesn't arrive prior to the new State of Israel being established.
1947 begins the 70th jubilee of a covenant for the Jews that began when they were in Egypt, beginning 3430 years earlier in 1435 BCE. Based on that, we can date the Exodus specifically 49 years later to 1386 BCE.
thus both CHRONOLOGY and specific EVENTS combine to confirm the "last generation" that would see the second coming prior to 1994, but not prior to 1948.