Isaiah 66

As we read the last writings in the record of Isaiah, the Lord again teaches of whom will be the house of Israel throughout eternity being -

"For all those things hath mine hand made, and all those things have been, saith the LORD: but to this man will I look, even to him that is poor and of a contrite spirit, and trembleth at my word."  (Old Testament | Isaiah 66:2)

Which -

"Hear the word of the LORD, ye that tremble at his word;.."  (Old Testament | Isaiah 66:5)

 And in these last days, the Lord will hasten His work for the missionaries -

"...shall declare my glory among the Gentiles.
20 And they shall bring all your brethren for an offering unto the LORD out of all nations upon horses, and in chariots, and in litters, and upon mules, and upon swift beasts, to my holy mountain Jerusalem, saith the LORD, as the children of Israel bring an offering in a clean vessel into the house of the LORD.
21 And I will also take of them for priests and for Levites, saith the LORD.
22 For as the new heavens and the new earth, which I will make, shall remain before me, saith the LORD, so shall your seed and your name remain."  (Old Testament | Isaiah 66:19 - 22)

All the righteous being gentile or Jew will receive the priesthood and become His seed.