Whom is Hashem addressing?
Radak: He addresses the nation, like until now, and then he tells the Navi to answer them.
When will this be?
Radak: It is after the enemy exiles them. Malbim - then they will believe in Hashem and His punishments.
What is the question?
Malbim: For what sin is the exile, and how is it Midah k'Neged Midah?
How is the exile Midah k'Neged Midah?
Radak: You served foreign gods in your land. You will serve a foreign nation in a land that is not yours!
Malbim: Your land is under Hashgachas Hashem, and you abandoned Him and accepted to serve the idols of the previous residents. Also in a land that is not yours, you will serve foreigners, for you loved to serve foreigners!