Perek 43: Our redemption from Sancherev (Ashur) and future ingathering of the exiles. Our special relationship with HaShem and HaShem’s criticism of our lack of dedication to Him.
Perek 44: Our nation is still the chosen people, stupidity of idols, and future establishment of the Temple.
Perek 45: Cyrus made HaShem’s agent to bring the Jews back from Babylonia to Israel. Future times of HaShem’s revelation and the nations’ confession of HaShem’s Truth.
Perek 46: Collapse of idols.
Perek 47: Exile of the Babylonians
Perek 48: Prophecy’s correctness and reward for obedience.
Perek 45 tells us of the nations’ future admission of HaShem. The Brisker Rav points out a notable explanation in the Talmud on this subject. The Talmud tells that in the End of Days, HaShem will declare; ‘whoever occupied himself with Torah may now come and claim his reward.’ The nations of the world will then claim a share in this reward for ‘facilitating the Jew’s study of Torah.’ For example, the Romans will claim that all the silver and gold, and infrastructure was built only to allow the Jews to learn Torah. HaShem responds ‘fools! Everything you did was for your own benefit only.’ The Brisker Rav asks: what’s going on here. Do the non-Jews really think that they can pull the wool over HaShem’s eyes? And why does HaShem call them ‘fools;’ He should call them ‘liars?’ The Brisker Rav answers based on Rashi in the beginning of Bereishis (1:31) that the entire purpose of Creation is for the Jews to accept and dedicate themselves to Torah. Therefore, everything built, etc. is for the purpose of Torah. This is why the non-Jews were not lying; it was true, the bridges, gold, etc. was for our Torah. Just they did not intend for this purpose when they were building their empires and industries.