A smart observation. Thanks for continuing to engage, Robin. Though we are straying slightly from the original post, I always enjoy this kind of hearty discussion.
I still affirm that the generation Christ is referring to in Matthew 24 is the generation that he is speaking to in that context. Everything in that chapter pertains to 70AD.
Though I am an ESV guy, v.34, as I understand, is more accurately translated in the KJV “Then will appear the sign of the son of man in heaven”, that is, the sign does not appear in heaven but rather the sign appears that the Son of Man IS IN heaven. I.E. He is reigning in glory.
The temple is a small scale representation of the cosmos, like the tabernacle before it. The old world with its spiritual hierarchies is ended, His kingdom has come and has established a new cosmological rule. The Temple is no longer the center of true worship.
Cosmic language is often used throughout the OT (and is also used in Revelation) to speak of judgements on the land. Same thing is happening here. An “apocalypse” is a “revealing” and what will be revealed at 70AD and ever thereafter is that Christ is Lord, he is reigning, and he is making all his enemies his footstool. The kingdom advances, even in times like ours where it looks like it is weak and dying, and the enemies of Christ are organized and aiming to destroy God’s People. Nonetheless, Christ is on His throne and the world is becoming increasingly more Christianized.
I will posit that there are likely typological connections between Matthew 24 and Christ’s physical second coming. I am a bit of a typology nerd. And on that note, as for the millennial reign, I am of the perspective that it does typologically connect to the Sabbath but is not a literal 1000 years because Christ has already been reigning for 2000 years.