Deuteronomy 30:1-10 seems like an expansion of Deuteronomy 4:29-31, and sums up the promises of D, expressing them from the standpoint of the Exile.
Deuteronomy 30:1. the blessing and the curse: referring to Deuteronomy 28.
Deuteronomy 30:3. turn thy captivity: render, restore thy fortunes (Job 42:10).
Deuteronomy 30:6. circumcise thy heart: Deuteronomy 10:16 *.
Deuteronomy 30:7 f. The curse now resting on Israel will be transferred to their enemies.