NT Jewishness!

Yes there is no replacement. The Bible tells us that the Jews have been blinded for a time for the benefit of all mankind - so that the gospel could be offered to all men, but after the fulness of the Gentils has come in, God will once again return to bringing about the salvation of His remnant of the house of Judah so that ALL of Israel will be saved.

Romans 11:25-26 For I do not want you, brethren, to be uninformed of this mystery - so that you will not be wise in your own estimation - a partial hardening has happened to Israel until the fullness of the Gentiles has come in: and thus all Israel will be saved....

Romans 11:11 Did God’s people stumble and fall beyond recovery? Of course not! His purpose was to make his salvation available to the Gentiles, and then the Jews would be jealous and want it for themselves.
12 Now if the Gentiles were enriched because the Jews turned down God’s offer of salvation, think how much greater a blessing the world will share when the Jews finally accept it.

All Israel is both houses of Israel and the wild branches grafed in that Paul trys so hard to explain, using chapter 9, 10, and 11 of Romans.

Rom 11:18 stop being arrogant towards the branches. But if you are arrogant, [remember] _you_ do not sustain the root, _but_ the root [sustains] you!
19 You will say then, "Branches were broken off, so that _I_ should be grafted in."
20 Rightly [said]! They were broken off by unbelief, but _you_ have stood by your faith. Stop being conceited, _but_ be fearing.
21 For if God did not spare the natural branches, perhaps neither will He spare you.
22 Therefore, look at [or, consider] [the] goodness and severity of God: on the one hand upon the ones having fallen, severity; on the other hand upon you, kindness, if you remain in the goodness; otherwise, _you_ also will be cut off.
23 But also those, if they do not remain in unbelief, will be grafted in, for God is able to again graft them in.
4 For if _you_, the [one] by nature of the wild olive tree, were cut out, and contrary to nature, were grafted into a cultivated olive tree, how much more will these, the natural ones, be grafted into their own olive tree?
25 For I do not desire [for] you* to be unaware, brothers [and sisters], of this secret [or, mystery], so that you* shall not be wise in your* own conceits, that hardness in part [fig., partial stubbornness] has happened to Israel until the fullness of the Gentiles comes in.
26 And so all Israel will be saved, just as it has been written, "The One delivering will come out of Zion, and He will turn away impiety [or, ungodliness] from Jacob;

Gen 22:18 And in your Seed shall all the nations of the earth be blessed, because you have obeyed My voice.

I believe that the house of Israel, headed by Ephraim, the "firstborn" of God, is the "Church of the firstborn" or the Christians - the "born again" Saints. These are those Jesus said that He came for. The house of Judah is the Jews of whom God will once again show Himself to a remnant and they will morn for Him as a lost Sons and realize who He is during the tribulation of days.

Jeremiah 31:9 They shall come with weeping, and with supplications will I lead them: I will cause them to walk by the rivers of waters in a straight way, wherein they shall not stumble: for I am a father to Israel, and Ephraim is my firstborn.

Romans 8:29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that He might be the firstborn among many brethren.

Hebrews 12:23 To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect,

Matthew 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.

Zechariah 12:10 And I will pour out a spirit of compassion and supplication on the house of David and the inhabitants of Jerusalem, so that, when they look on the one whom they have pierced, they shall mourn for him, as one mourns for an only child, and weep bitterly over him, as one weeps over a firstborn.
11 On that day the mourning in Jerusalem will be as great as the mourning for Hadad-rimmon in the plain of Megiddo.
12 The land shall mourn, each family by itself; the family of the house of David by itself, and their wives by themselves; the family of the house of Nathan by itself, and their wives by themselves;
13 the family of the house of Levi by itself, and their wives by themselves; the family of the Shimeites by itself, and their wives by themselves;
14 and all the families that are left, each by itself, and their wives by themselves.
13:1 ¶ On that day a fountain shall be opened for the house of David and the inhabitants of Jerusalem, to cleanse them from sin and impurity.
2 On that day, says the LORD of hosts, I will cut off the names of the idols from the land, so that they shall be remembered no more; and also I will remove from the land the prophets and the unclean spirit.