Only way to really know is to 'pay attention' to all... of the Isaiah 17 chapter, not just pieces of it like many preachers do with their chopping up God's Word just to create a Sunday one hour sermon.
Isa 17
17 The burden of Damascus. Behold, Damascus is taken away from being a city, and it shall be a ruinous heap.
2 The cities of Aroer are forsaken: they shall be for flocks, which shall lie down, and none shall make them afraid.
"Aroer" is Hebrew for 'nudity of situation' (OT:6176). The idea here is about these cities being in a waste state, and the flocks take them over as pastures.
3 The fortress also shall cease from Ephraim, and the kingdom from Damascus, and the remnant of Syria: they shall be as the glory of the children of Israel, saith the LORD of hosts.
Refers to both historical northern "kingdom of Israel" with one of the tribe of Ephraim as its king, but also at the end regarding Ephraim being in a waste state (see Isaiah 28). Notice in Revelation 7 that Manasseh is mentioned, but Joseph is put instead of Ephraim.
4 And in that day it shall come to pass, that the glory of Jacob shall be made thin, and the fatness of his flesh shall wax lean.
This is not just about the Jews, nor the northern kingdom (ten tribes) through history. This is pointing to all... the children of Israel, everywhere. Possibly pointing to the time of sorrows just prior to the great tribulation.
5 And it shall be as when the harvestman gathereth the corn, and reapeth the ears with his arm; and it shall be as he that gathereth ears in the valley of Rephaim.
The Rephaim was a name for the giants. This idea is that it won't be safe to even go out in the fields to pick crops because of the danger.
6 Yet gleaning grapes shall be left in it, as the shaking of an olive tree, two or three berries in the top of the uppermost bough, four or five in the outmost fruitful branches thereof, saith the LORD God of Israel.
The gleaning grapes, two or three berries left, etc., represent God's elect. To me it says there will be some that will know the truth even in the time of the end, during sorrows and danger.
7 At that day shall a man look to his Maker, and his eyes shall have respect to the Holy One of Israel.
What time on earth would especially cause the believer to look to his Maker for deliverance? I'd say it's the time of great tribulation for the end of this world.
8 And he shall not look to the altars, the work of his hands, neither shall respect that which his fingers have made, either the groves, or the images.
This is pointing to a time like the end of Joel 2 I believe, which is about a time just prior to the "day of the Lord" (i.e., just prior to the day of Jesus coming).
9 In that day shall his strong cities be as a forsaken bough, and an uppermost branch, which they left because of the children of Israel: and there shall be desolation.
This continues the state of the one who looks to his Maker for help in evil times.
10 Because thou hast forgotten the God of thy salvation, and hast not been mindful of the rock of thy strength, therefore shalt thou plant pleasant plants, and shalt set it with strange slips:
11 In the day shalt thou make thy plant to grow, and in the morning shalt thou make thy seed to flourish: but the harvest shall be a heap in the day of grief and of desperate sorrow.
This points even more to a time of desolation, because of their planting "strange slips", i.e., idol worship.
12 Woe to the multitude of many people, which make a noise like the noise of the seas; and to the rushing of nations, that make a rushing like the rushing of mighty waters!
13 The nations shall rush like the rushing of many waters: but God shall rebuke them, and they shall flee far off, and shall be chased as the chaff of the mountains before the wind, and like a rolling thing before the whirlwind.
That reveals this is not just about the city of Damascus, but about nations gathering together like a great noise of the seas, rushing like mighty waters, and then God rebukes them like chaff of the mountains before the wind. That's about the end, the gathering of nations that go upon Israel to prey at the end of this world, and then God comes off His throne in anger at them, a la Ezekiel 39 and Revelation 16 on the 7th Vial.
14 And behold at eveningtide trouble; and before the morning he is not. This is the portion of them that spoil us, and the lot of them that rob us.
KJV
Those that spoil Israel, is the idea. That destruction is about the nations to gather up against Jerusalem on the last day of this world. So the previous parts of Isaiah 17 may indeed have been historical, but this is also about the very end of this world also.