"The utter destruction of them as a people, for just as Israel was destroyed before Isaiah, by the Aramite Assyrians, the Aramites would be destroyed by the Babylonians."
You are confusing Assur and Aram. Assyria was made up of them both. "Assyrians" were invaders from the northern land of Assur (thought to be on the eastern coast of the Black Sea), and were an elite class over the (more-or-less native) Aramites, who had naturally drifted south and east from their origins (probably Turkey).
AFAIR, when Babylon conquered Assyria, it didn't exactly conquer Assur, but merely drove them far to the north, back to their ancestral lands, but did receive dominion over the land of Syria and the Aramites.
So one could also suggest that the prophecy against Damascus was against the people of Assur rather than the people of Aram, who have continued much as you have described through a long series of dominant empires. It hardly seems fair to punish the underclass for what their overlords had done.
The most straightforward reading of the prophecy would be in the most literal sense. It also seems to take place at a time when Ephraim returns to occupy his native soil, and i so populous that he spills out into all the regions South of Damascus, as reported in Isaiah and Zechariah (among others).
I believe that time to be the aftermath of the War of Gog and Magog, yet prior to the time of the end.
>> The most straightforward reading of the prophecy would be in the most literal sense. <<
I don’t get either sense as being more “literal.” There’s ambiguity as to what “Damascus” refers to, and who’s abandoning Damascus’ cities, not a sense of one meaning being more literal than another.
And I don’t find your distinction between Aram and Assur supported; in any case, what I wrote about the Aramites holds true for the Assurites, so your distinction changes nothing. (I researched Aram, finding that they were Assurites, which redircted my to Assyrians, and them proceeded to describe what became of them.) In any sense, the reason I refered to Aram is because that’s who the prophecy on Damascus specifically refers to. It certainly would be wierd to refer to Aram and the Aramaic city of Damascus when what was meant was the Assurites, who still kept Assur as their religious capital, no?