Isaiah 19 introduces the next oracle against the nations of the earth. The Lord has been showing His people not to put their trust and hope in the foreign nations or their gods. They are to trust in Him alone to save them. The Lord's arrival in Egypt reveals the worthlessness of idols and spiritists. The terrified people will turn on each other. They will become destitute when the Nile dries up and the wise are shown to be foolish. In the far future, Egypt will worship the Lord and be blessed by Him.

Source: bibleref.com

Isaiah 19 contains a prophecy regarding Assyria that describes the condition of the Middle East during the millennial reign of Christ. The repeated phrase in that day in Isaiah 19 is a reference to the day of the Lord, when He sets all things right. According to Isaiah’s prophecy, Assyria (modern Iraq) will join Egypt and Israel in serving the Lord (Isaiah 19:23), and there will be political unity among Egypt, Israel, and Assyria. All three nations will be blessed by God (verse 25) and be a blessing to other nations (verse 24). Jesus truly is the Prince of Peace who can bring unity to these three former enemies. Because of Jesus, the future of Assyria is bright.

Source: gotquestions.org