I will strike the winter house with the summer house; And the houses of ivory will perish, And the great houses will have an end," says Yahweh.
"The horns of the altar shall be cut off ..." The horns of the altar were supposed to be its most sacred part; and, in pagan societies, a criminal could claim refuge by taking hold of the horns of the altar; but this was not allowed in Israel.  Joab attempted to do this but was executed in spite of his doing so (1 Kings 2:28ff).  The meaning is simply that the whole religious apparatus at Bethel shall perish, along with the rest of Israel.