The prophets spoke the words of God, and they are never irrelevant. Isaiah told the king of Judah that when his wife had born a child and got that lad to the age of reason the current kings who oppressed Israel would disappear. But the prophecy foretold Mary bringing Jesus into the world, and the fears of Joseph.
For he feared for Mary, and for himself. With reason.
In this time, we have the completed work of Jesus, whose birth is still proclaimed at this time. It is very good to speak of Jesus now: the gospel should be preached ‘in season and out of season’.
But also expect that the kings that you fear will disappear. My reading of history is that they always do.
10 Then the Lord spoke again to Ahaz, saying, 11 “Ask a sign for yourself from the Lord your God; make it deep as Sheol or high as heaven.” 12 But Ahaz said, “I will not ask, nor will I test the Lord!” 13 Then he said, “Listen now, O house of David! Is it too slight a thing for you to try the patience of men, that you will try the patience of my God as well? 14 Therefore the Lord Himself will give you a sign: Behold, a virgin will be with child and bear a son, and she will call His name Immanuel. 15 He will eat curds and honey at the time He knows enough to refuse evil and choose good. 16 For before the boy will know enough to refuse evil and choose good, the land whose two kings you dread will be forsaken.
18 Now the birth of Jesus Christ was as follows: when His mother Mary had been betrothed to Joseph, before they came together she was found to be with child by the Holy Spirit. 19 And Joseph her husband, being a righteous man and not wanting to disgrace her, planned to send her away secretly. 20 But when he had considered this, behold, an angel of the Lord appeared to him in a dream, saying, “Joseph, son of David, do not be afraid to take Mary as your wife; for the Child who has been conceived in her is of the Holy Spirit. 21 She will bear a Son; and you shall call His name Jesus, for He will save His people from their sins.” 22 Now all this took place to fulfill what was spoken by the Lord through the prophet: 23 “Behold, the virgin shall be with child and shall bear a Son, and they shall call His name Immanuel,” which translated means, “God with us.” 24 And Joseph awoke from his sleep and did as the angel of the Lord commanded him, and took Mary as his wife, 25 but kept her a virgin until she gave birth to a Son; and he called His name Jesus.