This is a very good question and well done for bringing this matter up.
Yes Supercessionism, otherwise known as Replacement Theology, came in with Augustine, actually. It basically says that the Church has replaced Israel in the scheme of things. Now - it says - the Church are the people of God and chosen, and Israel is just a people like any other people.
Not true. (Ro 11:29) 'For the gifts and calling of God are without repentance'.
Now, read that passage in its context, and you will see Paul is not talking about the gifts of the Spirit, he is talking about Israel, and her election. And he is saying that God has not taken back his choosing of Israel. See, it is here again in the previous verse:
Ro 11:28 '... as touching the election, they are beloved for the fathers’ sakes'.
Also, when you look at 'the cutting of the covenant', when God made a covenant with Abraham and passed between the sacrifices (Gen.15:17), it was a one-sided covenant, because Abraham was in a sleep, so only God passed between the sacrifices. That means that it was only up to God to keep the covenant (a covenant to bless his people and give them the land). It was therefore a covenant without conditions as far as Abraham (and his people) were concerned, but not as far as God was concerned. Therefore, that covenant still stands - to bless Abraham and his children (through the seed of Isaac) for no man could annul it.
So, what you have read in Deuteronomy is right, the Jews are still chosen, the elect people of God. But what has happened is that there is come, since Pentecost, another elect and chosen people (this time spiritual, as the Jews are God's natural people), which has largely come out of believing Gentiles. God has never cast the Jewish people off - though, for sure, they have suffered much - but now he has added to that favoured people another people, which is the community of the redeemed, the Church.
If you read the book of Acts, you will see that Paul always went first to the synagogues on his missionary journeys, he always preached 'to the Jew first'. After a while, the Jews dogging him and baiting him exasperated him, and you see towards the end of Acts that he declares he will go henceforth to the Gentiles. But, annoying as Jews can be, they have by no means exasperated God! And he has not cast them off - read Roms. 11:1.
Also, if you study the Bible - particularly the prophets, you will see that it is not true that the Jews are a people with no special future. According to Bible prophecy, there is very much yet to happen to the Jewish people in the End Times.
Read the Book of Revelation too. You cannot understand it because you have missed the Jews out. It is a very Jewish book, just like Daniel is. Can you find the Jews in there? Yes, they are the 144,000 JEWISH evangelists (ch.7), the two Prophets (ch.11) and the woman 'robed with the sun' in ch.12. What do you think?