Isaiah 11:16 (NKJV)
16 There will be a highway for the remnant of His people Who will be left from Assyria, As it was for Israel In the day that he came up from the land of Egypt.
And then Chapter 12 breaks out in a song of praise. The song is in the singular ("I" and not "we") and so we could translate the beginning as "Each of you will say in that day." There is an important emphasis on the individual's decision to trust and obey the LORD here. Most of the consequences that have been written about in Isaiah thus far are national issues as a whole. But Ahaz had to make His own decision (Isaiah 7:9b) and every other Israelite must as well (Isaiah 28:16).