It’s not an odd question considering the Preterist doctrine of all prophecy being fulfilled in 70 AD.
You are implying that “this generation” means the generation of human beings existing in 70 AD.
The Scripture plainly states that “this” generation (the one that Jesus is speaking of) is the generation that witnesses:
1) A tribulation that has never been seen before or ever will be witnessed.
(WWII and the Holocaust far exceeds any Judeaen-Roman war; the Stalinist and Maoist famines exceed any Roman seige famine that preceeded it, etc.)
2) The sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken.
(Was there a solar and lunar eclipse in that region of the world in that time period? And how about the “powers of heavens shaken”?)
3) The sign of the Son of man in heaven.
(The closest thing we have in history to this was the cross appearing to Constantine in 312 AD - over 200 years after the Temple was razed)
4) All the tribes of the earth mourn.
(Didn’t happen)
5) [All tribes of the earth] shall see the Son of man coming in the clouds of heaven with power and great glory.
(Didn’t happen)
6) [Jesus] shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.
(The OPPOSITE of this happened - the Diaspora. Only in 1948 in the founding of Israel did anything like this start happening.)
Along with all other prophecy previously mentioned.
As I explained in detail above, I don’t believe anyone in 70 AD saw any of these things happen. Therefore, “this generation” is not the generation from 70 AD.