It seems to me that Paul is addressing prejudice in Rom 9 - 11, essentially saying that Israel were chosen for a purpose, but God's mercy is extended to all.
These verses are telling:
6 This does not mean that God’s word has failed, because not all who are descended from Israel are really Israel, 7 and not all who are descended from Abraham are really his children. On the contrary, “Your line of descent will be traced through Isaac.” 8 This means that it is not the children of the flesh who are God’s children, but it is the children of the promise who are counted as his descendants. 9 For this is what the promise said: “I will arrive at this set time, and Sarah will have a son.”
I think he is repeating what John the Baptist said, in Matthew 3:9 -
"And do not presume to say to yourselves, ‘We have Abraham as our father,’ for I tell you, God is able from these stones to raise up children for Abraham."
No one must think that salvation comes from blood - from ethnicity, race, culture, colour of skin, etc. He is arguing against such prejudice. Salvation comes by the blood of Jesus, not our bloodline. It comes due to the grace and mercy of God and by faith - and now He chooses to have mercy on the gentiles. (The word "gentiles" means "nations"). God responds to faith, not DNA.
I do think that to go beyond this and use the scripture to create a new form of prejudice (the "elect" vs the "damned") is ironically going against the very point Paul is making in these verses. Predestination in the Calvinist sense may or may not be true, but to use this scripture to show it I think goes against what is being shown in it.