I will argue that these 2 trees stand for Israel as respectively a political and religious system and that the olive branches are about the continuation of true worship. For, spiritually, the fig tree was condemned by Christ for not having (religious) fruit. You must know that a healthy fig tree normally bears early fruit, therefore Christ was not unduly angry, as some say, to have it withered from the root; even though it was not yet the time of (full) fruit. Politically, He said: "Have faith and say that this sycamore tree is uprooted and be planted in the sea (of nations)." That is what the Romans did in the year 70 A.D. And as to Worship, remember that the apostle Paul, in Romans (chps. 9-11), warns that the Church; if it fails, can be pulled out as the wild olive branches and that the normal branches can be regrafted upon the tree that began, of course, with Abel and his true worship. Think also of the parable of the fig tree in Luke 13 that was unfruitful already for 3 years and that got another chance of a year. This is to be applied to the fact that the Lord preached from about his thirtieth to his thirty-third year and a half. The remaining half year, one could say, stands for the fact that the apostles first preached to Jewry, but they rejected Christ also then and the apostle Paul declared them guilty and went to the gentiles. "Wrath to the end" he predicted for them. And this wrath will remain on them till they realize that they have murdered their own Messiah and then they will truly repent, nationally so. (But woe to them that carry out this wrath. The Roman Church, in the crusaders and at other occasions, drew the sword against them and therefore they will be ended by the sword. It would not surprise me; certainly not after the Rapture [the taking up of all true believers in the (Shekinah) clouds: 1 Cor. 15. 51 and 1 Thess. 4. 13-18]).
As Christians we should not boast and we must realize that we have thoroughly failed. Also the epistle to the local assembly at Laodicea is predictive of today's lukewarm Christendom that will, as it says there, 'be vomited out.' Also Hoshea predicts, after declaring Israel 'Not-my-people,' that it will be revived after 2 days and on the third day. The declaration of not being the Lord's people went into effect at the end of the 69th week of the book of Daniel [see also The 7 Days of Human History and its 13 Kings]). For it says, in chapter 9. 26 'and Messiah . . . will have nothing (the correct translation).' And it began when the Shekinah cloud left the temple, at the beginning of Ezekiel (God is slow to anger and longsuffering). When the 69 weeks began, is all explained in the bible, in Daniel, and very much verifiable in secular history (in this case begin with reading through the book of Daniel and comparing it prayerfully and independently, from your usual teachers, with the book of Revelation). Now Christ was cut off (will have nothing) at the cross and he had already predicted that "hell will not overwhelm the Church". But that does not mean that the earthly testimony of so-called Christians (deliberately with a small 'c') will not come to an end, let alone that Israel has been supplanted by the Church for ever. They will co-exist unto the ages of the ages, for Christ will spiritually marry the Church in heaven one day (therefore spiritual marriage rings with Christ are out of order, or call them betrothal rings; for the apostle "betrothed" the Church "as a pure virgin to Christ"); and His earthly kingdom, starting in the Millennium, will be an eternal kingdom, in accordance with the prophecy in Daniel. This symbiosis will be spearheaded for ever in both the heavenly (see the last chapters of the bible) and the earthly Jerusalem, for the Church has a heavenly calling and Israel has an earthly calling.
The word for 'sycamore' is also translated as 'wild fig tree'. That is a serious thought, for without the cultivated (by the Lord) fig tree and the true olive branches, all that Israel has is a wild political system that stands alone in a sea of nations; without the real blessing of God.
As to the fact that there are 70 weeks of each 7 years, many bible expositors see that as historical without realizing that there is still 1 week of 7 years to come. That this is so is clear from the text that tells that Israel will yet have to make a "covenant with hell (and who else is that but with the beast of Revelation 13!) (Is. 28. 15, 18) and from other texts where it is explained that Jacob's trouble still is to come and that 'their hand will be pierced by a reed, on which they lean' until they learn to trust on the Lord only. There are many prophecies that are to be fulfilled yet in the (far) future (read for instance the prophecy of the attack by Gog and Magog [Mesech must be Moscow] (Ez. 37 & 38)). Many overly enthusiastic Christians think, or thought, that prophecies such as that "the desert will bloom" are or have been accomplished in our days; as Jewry has cultivated some parcels here and there. But this is nonsense. Jewry, even according to some of their own orthodox rabbis, has done everything largely in their own power and with luck (that is explained as miracles from the Lord). Yet this must also be a paradox, as nothing happens without the, at least indirect, guidance of God. It must have to do primarily with the continuation of Jewry as a general phenomenon. But, I at least, do not begrudge them the resurrection of their sycamore tree, of their political system. Perhaps the "bones," according to the prophecy (Ez. 37), are finally coming together, after all. But the coming of the cultivated fig tree and certainly of the regrafted natural olive branches, is still a long way off. The 5th day of human history still has to intervene, when Israel will be provoked to jealousy by a 'foolish nation' through bearing 'its fruit.' Christendom is not this nation.