God’s promise that David's lineage would be on the throne forever had an immediate impact on David’s parenting.
When we train our children well, we should expect our kids to want to flee temptation. We should expect our loved ones who profess the name of Christ to live holy and righteous lives. We should expect that our Christian family members to be a light in the darkness. We should expect these things not in a “you’d better perform” kind of way, but expecting these things because God is at work, and he is faithful to his promises.