When Christ came, he established the kingdom through Peter (Daniel 2:44, Matt 16:18). However, the prophecy was clear of the falling away, as well as the defeat of the saints to the dragon (2Thes 2:3, Rev 11:7, 13:7, Dan 7:21). The prophecy is also clear that Israel will not be gathered in Christ (Isaiah 49:5).

It seem clear to me that the fall of the saints refers only to the Jews. Christ was only sent to the Jews (Matt 15:24). The first evangelization was actually directed to the Jews, of which Paul said to them, "it was NECESSARY that the word of God should FIRST have been spoken to you(Jews)." (Acts 13:46). Why it was "necessary" and that it should be "FIRST" be spoken to the Jews? The simple answer to this is that salvation would not come to the Gentiles not until the Jews fall away(Rom 11:11-12). The disciples are Jews themselves. And as long as there are Jews that hold the doctrine of Christ, the promises would remain to the Jews.

The falling away is utter that Jesus himself said of that time, "...IF ANY MAN shall say to you, Lo, here is Christ; or, lo, he is there; believe him not:"(Mark 13:21). It is difinitely what the prophecy in Amos of the famine of the word, and that men "shall not find it" (Amos 8:11-12).

But what happened to the Gentiles that believed the disciples? The Gentiles were saved but they still have no authority of priesthood, especially because the Jews had not yet fallen. Rather,Jamess said:

14 Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name. 15 And to this agree the words of the prophets; as it is written, 16 After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up: Acts 15:14-16

It is clear to me that the tabernacle that James was referring is the tabernacle, or church, that he established through Peter (Matt 16:18), and which Peter himself said that "shortly I must put off this my tabernacle, even as our Lord Jesus Christ hath shewed me." (2Pet 1:14).

What is not noticed by many is that Christ will be received by the Gentiles(Isaiah 11:10, 49:6), but the gentiles does not refer to the gentiles at the time when the Jews are still standing, or had not fallen away yet. The Jews will surely come back to the fold of the church. But the blindness of Israel, or their fall, would meant of a certain time in which the Jews had no part in the ministry of the priesthood. Thus, what James refering as Gentiles were not belonging to Gentiles of their time; seeing they Jews had not yet fallen. Not to mention, James was clearly speaking of a future of taking out a Gentile nation.

Paul himself spoke of gentiles that will believe in the future (Act 28:28). Actually, Paul's was being sent to these gentiles in the future (Acts 13:47, 28:28, Rom 15:20-21, 2:16). The Gentiles that believed during the time of Christ were converts through Peter (Acts 15:7), thus is why Paul was hindered coming to these Gentiles to avoid he might "build upon another man's foundation."

So there will come a time when no Jews will be sitting in the kingdom of God. Even Christ's prophecy is very clear, saying, "

11 And I say unto you, That many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven. 12 But the children of the kingdom shall be cast out into outer darkness: there shall be weeping and gnashing of teeth. Matt 8:11-12

Even Isaiah's prophecy is very clear:

1 I am sought of them that asked not for me; I am found of them that sought me not: I said, Behold me, behold me, unto a nation that was not called by my name. 2 I have spread out my hands all the day unto a rebellious people(Israel), which walketh in a way that was not good, after their own thoughts; Isa 65:1-2

Even Malachi is clear of these things:

11 For from the rising of the sun even unto the going down of the same my name shall be great among the Gentiles; and in every place incense shall be offered unto my name, and a pure offering: for my name shall be great among the heathen, saith the LORD of hosts. 12 But ye(Jews) have profaned it, in that ye say, The table of the LORD is polluted; and the fruit thereof, even his meat, is contemptible. Mal 1:11-12

Further prophesies:

10 Sing unto the LORD a new song, and his praise from the end of the earth, ye that go down to the sea, and all that is therein; the isles, and the inhabitants thereof.Isa 42:10

5 Behold, thou shalt call a nation that thou knowest not, and nations that knew not thee shall run unto thee because of the LORD thy God, and for the Holy One of Israel; for he hath glorified thee. Isa 55:5