If you check the descriptions and Scripture references for "telos" and "sunteleia", you will see significant differences.
"Sunteleia" virtually always refers to the Second Coming.
"Telos" does not.
This is true! I agree that Christ is saying the Old Covenant ends, so the New Covenant through Christ would be established. I think you and I are in agreement on that much. But I don't believe the end for Old Covenant Israel was the literal destruction in AD 70. I believe it ended with the crucifixion of Christ. When His body, which was the True Temple became a sacrifice for sin. But this truth was not clearly understood and would not be made known as long as the city and temple continued to stand. That is the time of reformation that would come through Christ. Even the disciples would not fully understand the end of the Old and beginning of the New, that would also have its end, until Pentecost.
Hebrews 9:8-10 (KJV) The Holy Ghost this signifying, that
the way into the holiest of all was not yet made manifest, while as the first tabernacle was yet standing: Which was a figure for the time then present, in which were offered both gifts and sacrifices, that could not make him that did the service perfect, as pertaining to the conscience;
Which stood only in meats and drinks, and divers washings, and carnal ordinances, imposed
on them until the time of reformation.
On the Day of Pentecost, Peter, being filled with the Holy Spirit preached the time for the prophet Joel's prophecy had begun to be fulfilled. Peter preached of the New Covenant that had come through the sacrifice of Christ. Now "all" people. All without distinction, not all without exception, but all people of faith would be saved. The Old Covenant was gone and the New had come because the long-awaited Messiah had come.
Acts 2:16-17 (KJV) But this is that which was spoken by the prophet Joel; And
it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams:
Acts 2:21 (KJV) And it shall come to pass,
that whosoever shall call on the name of the Lord shall be saved.
I believe the way that makes sense (at least to me) in understanding the prophetic words Christ spoke, is to understand He spoke of two separate endings, not only the end that shall come when the seventh angel begins to sound that time shall be no longer.
Christ began His discourse by basically telling His disciples not to think too highly of the city and temple that was long admired. For neither the city nor the buildings would remain. All would be utterly destroyed forever. The disciples would understand the spiritual significance of Christ's statement through the Holy Spirit, they would then remember the words Christ spoke of the Temple He was pointing them to that would become the True Holy Place, that is His body, broken for them and for us (all who are of faith).
This is how we too can know that the Old Covenant ended through the shed blood of Christ. And the New Covenant age, that also has an end, had come. The time of the Lord began, and the time for obedience to the Law and Prophets is fulfilled in Him by grace through faith as ALL whoever shall hear the Gospel and believe for everlasting life.
Matthew 24:2 (KJV) And Jesus said unto them,
See ye not all these things? verily I say unto you, There shall not be left here one stone upon another, that shall not be thrown down.
John 2:19-22 (KJV) Jesus answered and said unto them,
Destroy this temple, and in three days I will raise it up. Then said the Jews, Forty and six years was this temple in building, and wilt thou rear it up in three days? But he spake of the temple of his body.
When therefore he was risen from the dead, his disciples remembered that he had said this unto them; and they believed the scripture, and the word which Jesus had said.