The Lord Jesus Christ is the predominant figure in the Scriptures, not Israel, as some would have us believe. A remnant played an important role in God’s plan of redemption, from Abel to Jacob (Israel), and subsequently Old Covenant Israel, nevertheless, the focus has always been the Lord Jesus Christ.
Deu 31:29 KJV For I know that after my death ye will utterly corrupt yourselves, and turn aside from the way which I have commanded you; and evil will befall you in the latter days; because ye will do evil in the sight of the LORD, to provoke him to anger through the work of your hands.
The Old Covenant Age was never meant to be permanent, Israel anticipated the Messianic Age. The two covenants running parallel was never an option. Moses prophesied blessings and curses on Old Covenant Israel. He also prophesied the coming Messiah in the ‘latter days’ of the Old Covenant Age…Deuteronomy 18:15; John 1:45.
Before the Old Covenant could pass away, the Law, the Prophets , and the Promises had to be fulfilled, only the Messiah could achieve this to the letter.
At His return in AD 70, Christ fulfilled all remaining prophecy. He used the Roman Army to bring judgement on the Jews, which fulfilled the ‘times of the gentiles’ as instruments of the Lord’s judgement on Old Covenant Israel. Thereby, He ended the Old Covenant Age and established the New. Now, there is neither Jew nor Gentile, but one new man.