What part of “will no longer be a city” is difficult to understand for you?
Check out Adam Clarke's commentaries. Actually, most any commentary except for the misleading "Scofield's Reference Notes." This prophecy was fulfilled about 730 BC, and it was relating to the kingdom of Damascus (Syria,) which was in an alliance with Ephraim (the kingdom of Samaria) against Judah. But if you insist on taking the verse literally, where is Aroer?
This is from the Orthodox Jewish Bible:
"The massa (burden) of Damascus. Hinei, Damascus is taken away from being a city, and it shall be a heap of ruins. The cities of Aroer are deserted; they shall be for adarim (flocks), which shall lie down, and none shall make them afraid. The fortified city also shall cease from Ephrayim, and the mamlechah from Damascus, and the remnant of Aram (Syria); they shall be like the kavod Bnei Yisroel, saith Hashem Tzva’os." ([Isaiah] Yeshayah 17:1-3 OJB)
The Hebrew translation for "is taken away" can be literal or figurative; and is not definite. The King James reads similar to the OJB:
"The burden of Damascus. Behold, Damascus is taken away from being a city, and it shall be a ruinous heap." (Isaiah 17:1 KJV)
If you insist that everything in the Old Testament be taken literally, you have to contend with a multitude of translations of the original Hebrew; as well as a multitude of OT passages that contradict dispensationalism. For example you have to contend with passages like Ezekiel 48:1:2, which gives a land grant to the tribe of Dan. And there are these verses:
"And David my servant shall be king over them; and they all shall have one shepherd: they shall also walk in my judgments, and observe my statutes, and do them." (Eze 37:24 KJV)
"But they shall serve the Lord their God, and David their king, whom I will raise up unto them." (Jer 30:9 KJV)
"Therefore will I save my flock, and they shall no more be a prey; and I will judge between cattle and cattle. And I will set up one shepherd over them, and he shall feed them, even my servant David; he shall feed them, and he shall be their shepherd." (Eze 34:22-23 KJV)
So, who will rule during the so-called "thousand year reign:" David or Christ?
Philip