Isaiah 17:1-2
1 An oracle concerning Damascus.
Behold, Damascus will cease to be a city
and will become a heap of ruins.
2 The cities of Aroer are deserted;
they will be for flocks,
which will lie down, and none will make them afraid.
In other words, we don’t need to look for the fulfillment of Isaiah 17 today because it has already occurred—taking place in 732 BC.
The larger context of Isaiah also supports this interpretation. For example, in the previous chapter Isaiah speaks against Moab. This prophecy has already been fulfilled as well. Many of the predictions in this section of Isaiah were related to events that took place during or near the lifetime of Isaiah.
You might object by saying "Damascus will cease to be a city", but this is not a statement about Damascus for the entirety of history, but rather during that time period. This cannot be the deciding factor regarding whether the prophecy has already been fulfilled or not.
remember that Tiglath-pileser had carried away the people of Damascus to Kir, in the fourth year of Ahaz ( 2Ki 16:9); but now in Hezekiah's reign a further overthrow is foretold ( Jer 49:23, Zec 9:1 ).