I have a feeling this has to do with the fall of Israel, not the Catholic Church. Given that the Church is a global institution and not just a kingdom like Israel, which had fallen multiple times.
Also the prophecies contained in the first part of the book of Isaiah refer to the period in which Isaiah himself lived. In the year 738 the political horizon of the Near East was overshadowed by the growing threat of the military strength of Assyria, which was ruled at the time by Tiglath- Pileser III (724727). The northern kingdom (Israel) had fallen to the Assyrians in 721, and Judah, in the south, had become a vassal of Assyria and was about to succumb politically and spiritually in the reign of Ahaz.
So it does seem to make sense that this passage has to do with Israel