Isaiah has condemned the wicked actions of a house of Jacob gone astray. He now returns to the future picture. At that time when the Lord will establish peace, the wicked will be destroyed. Because Isaiah has just included the house of Jacob among the wicked, these are consequences that are to come upon them. They cannot escape by claiming that others are the guilty.
Therefore, they will fear the Lord. They will recognize that they have departed from God’s laws, and will seek to avoid the coming punishment. There are many caves in Israel, and they were historically used as places of resort in times of trouble. Isaiah tells them that they will seek out such resort from the coming righteous wrath of God.
However, it is a wrath upon all the wicked, not just Israel. Those in Israel who are haughty will be brought down, but so will those in other nations. Jehovah is the Lord of Hosts, the God of the whole world, not just of the house of Jacob. Therefore, this final wrath is upon all the wicked.