[Staff Edit]
Logic says that both positions can't be correct. At least one of those positions has to be incorrect. Either the position that insists this generation has already passed, or the position that insists it is yet to pass away.
Luke 21:32 Verily I say unto you, This generation shall not pass away, till all be fulfilled.
Jesus makes it unmistakably clear here, therefore, not one single person has an excuse that Jesus wasn't being crystal clear here, therefore, it is not debatable as to what He meant here. What did He say here? He said---till all be fulfilled---therefore, in the meantime this generation will not pass away. That means everything recorded in these accounts, prior to Him having said that, that all of it has to be fulfilled before this generation passes away.
Since it is Preterists insisting this generation has passed away, it is therefore them that need to prove what they allege.
Keep in mind, to be fulfilled means once it has been fulfilled it doesn't continue to be fulfilled nor is it fulfilled in future generations as well, it means it has been fulfilled, period. An example. Jerusalem and the 2nd temple were destroyed in 70 AD. That has been fulfilled, period. Thus nothing that continues to be fulfilled nor something that is fulfilled in future generations.
Let's label these A) B) in regards to fulfilled.
A) An example. Jerusalem and the 2nd temple were destroyed in 70 AD.. That has been fulfilled, period. Thus can't fit an example like B) below.
B) An example. And this gospel of the kingdom shall be preached in all the world for a witness unto all nations. It continues to be fulfilled. Therefore, it continues to be fulfilled in future generations. Therefore, it can't at the same time be both fulfilled before this generation passes away then continue to be fulfilled after it passes away, and then insist it has been fulfilled before this generation passes away. It has to be one or the other since fulfilled means it is no longer being fulfilled once it has been fulfilled. And Jesus plainly said all must be fulfilled before this generation passes away.
In order for one's interpretation to agree with what Jesus said in Luke 21:32, everything Jesus said prior to saying that, it must fit the definition of A) not B). Otherwise, this means Jesus lied to us if this generation passed away before everything He said fits with an example like A) rather than an example like B).
Luke 21:8 And he said, Take heed that ye be not deceived: for many shall come in my name, saying, I am Christ; and the time draweth near: go ye not therefore after them.
In regards to this generation passing away, does this fit the definition of an example like A) or the definition of an example like B), meaning once this generation has passed away? IOW, is anything in Luke 21:8 still true after this generation passes away? Or is it only true before this generation passes away? The former fits an example like B). The latter fits an example like A).
Luke 21:17 And ye shall be hated of all men for my name's sake.
In regards to this generation passing away, does this fit the definition of an example like A) or the definition of an example like B), meaning once this generation has passed away? IOW, is 21:17 still true after this generation passes away? Or is it only true before this generation passes away? The former fits an example like B). The latter fits an example like A).
Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.
In regards to this---until the times of the Gentiles be fulfilled---does this fit the definition of an example like A) or the definition of an example like B), meaning once this generation has passed away? IOW, is that part still being fulfilled after this generation passes away? Or is it only true before this generation passes away, meaning the times of the Gentiles are fulfilled before this generation passes away? The former fits an example like B). The latter fits an example like A).
Matthew 24:7 For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.
In regards to this generation passing away, does this fit the definition of an example like A) or the definition of an example like B), meaning once this generation has passed away? IOW, is Matthew 24:7 still true after this generation passes away? Or is it only true before this generation passes away? The former fits an example like B). The latter fits an example like A).
This should be enough to make the point. In order for Preterists to be correct about Luke 21:32, none of these verses above can fit an example like B), they all must fit an example like A).