For I shall bring them into the land which I swore unto their fathers, which floweth with milk and honey; and they will eat and fill themselves, and wax fat, and will turn unto other gods, and serve them, and despise me, and break my covenant.
Deuteronomy 31:18 And I will entirely hide my face in that day for all the evils that they have wrought, because they turned unto other gods.
Deuteronomy 31:19 And now, write ye this song, and teach it to the children of Israel; put it in their mouths, that this song may be a witness for me against the children of Israel.
Deuteronomy 31:20 For I shall bring them into the land which I swore unto their fathers, which floweth with milk and honey; and they will eat and fill themselves, and wax fat, and will turn unto other gods, and serve them, and despise me, and break my covenant.
Deuteronomy 31:21 And it shall come to pass, when many evils and troubles have befallen them, that this song shall testify against them as a witness; for it shall not be forgotten out of the mouths of their seed; for I know their imagination which they are forming already this day, before I bring them into the land which I have sworn [unto them].
Deuteronomy 31:22 And Moses wrote this song the same day, and taught it to the children of Israel.
The verse centers on "shall", "bring", "land", "swore", "fathers", "floweth", "milk", and "honey". It is saying that the verse draws attention to "shall" and "bring", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 19's "And now write ye this song and..." into verse 21's "And it shall come to pass when...", so "shall" and "bring" belong inside that flow. In Deuteronomy context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "shall" and "bring" with trust shaped by these words, not by a vague optimism outside the passage.