God's Continuing Mercy.
This chapter begins by recognising that both the blessings and the cursings described in Deuteronomy 28 will finally have their effects. Moses was fully aware that God had not at this stage permanently given to His earthly people a heart to know, eyes to see, and ears to hear as he had said (Deuteronomy 29:4). It was he himself who had declared that they were a stiffnecked people (Deuteronomy 9:6) and needed to be circumcised in heart (Deuteronomy 10:16). He had certainly experienced enough in the wilderness to know how unreliable they were. He thus reluctantly had to recognise that Yahweh had given these warnings because He knew that they would necessarily be fulfilled. Man's sinfulness made it finally inevitable. Through these things Israel would have to learn their lessons.
But his confidence was also in the fact that God would fulfil His promises to the patriarchs. He knew that God would not fail in that. Thus he recognised that just as God had shown mercy when the people had been driven from the land in Deuteronomy 1:44, so would He do so again when the people were driven from the land in the future. He had already made that clear in Deuteronomy 4:27-30, and he repeats the same idea now.
The covenant relationship very much underlies this whole section. They would be removed because they broke the covenant. But Yahweh would again turn to them. They were therefore then to turn to Him. Then would they be restored when they submitted to His covenant again. Compare Hosea 14:4, ‘I will heal their backsliding, I will love them freely: for my anger is turned away from him.'