What Jesus was describing in Matthew 14, Mark 13, and Luke 21 was the end of the Old Covenant. The outward manifestation of that covenant, which was always designed to pass away (see the book of Hebrews), would become a reality when the temple, the priesthood, and animal sacrifices passed away. And as Jesus predicted, it all took place when the temple in Jerusalem was dismantled stone by stone in AD 70.
Those were the “last days” that Jesus and the NT writers were describing (e.g., Heb. 1:1-2; 1 Cor. 10:11; Heb. 9:26; 10:24-25; James 5:7-9; 1 Peter 1:20; 4:7).
In Matthew 24:3, Jesus was not predicting the “end of the physical world” (kosmos) but the “end of age” (aiōn), a period of time. We now live in the New Covenant with Jesus as our temple, prophet, priest, king, and ultimate sacrifice for our sins.
Read the rest here