“Jehovah will strike Egypt, striking and healing it; and they will return to Jehovah, and he will respond to their entreaties and heal them.”
In this prophetic context, Egypt represents the nations of the earth in general. (Re. 11:8)
God will strike them on his judgment day. (Re. 16:14,16)
Throughout the earth, individuals set apart for salvation will then be “healed” in every sense of the word: spiritually, morally, physically, mentally and emotionally. (Re. 22:1,2)
Who will be their deliverer? None other than God’s own son.
(Is. 19:20; He. 2:9,10,14)
In the mean time, there is ‘an altar in the midst of Egypt’ and a ‘pillar on its boundary’ in the sense that God’s servants can be found throughout the nations and yet conduct themselves differently than most of the world around them. (Is. 19:19; Joh. 17:15,16)
God’s servants worship him united and peacefully, regardless of their national origin. (Is. 19:23)
If you would like more details on the minor and major fulfillment of Isaiah’s prophecies, you can find it in the online book “Isaiah’s Prophecies” Volume 1 & Volume 2.