He shall not return into the land of Egypt, but the Assyrian shall be his king, because they refused to return.
He shall not return into ... Egypt - namely, to seek help against Assyria (cf. Hosea 7:11), as Israel lately had done (2 Kings 17:4), seeking the help of King So, after having revolted from the Assyrian, to whom they had been tributary from the times of Menahem (2 Kings 15:19). He shall be no longer able to go to Egypt, for he shall be a captive in Assyria. In a figurative sense, "he shall return to Egypt" (Hosea 9:3) - i:e., to Egypt-like bondage; also many Jewish fugitives were literally to return to Egypt when the Holy Land was to be in Assyrian and Chaldean hands. "He shall not return into ... Egypt" shows this prophecy was uttered after the league made with Egypt (2 hands. "He shall not return into ... Egypt" shows this prophecy was uttered after the league made with Egypt (2 Kings 17:4).
But the Assyrian shall be his king - instead of having kings of their own, and Egypt as their auxiliary.
Because they refused to return - just retribution. They would not return (spiritually) to God, therefore they shall not return (corporally) to Egypt, the object of their desire.