I think there is a difference between conditional declarations of God and unconditional determinations of God.
For instance, when God said, “I will destroy Nineveh in forty days,” He was speaking conditionally upon the Assyrians’ response. His message to Nineveh was a warning meant to provoke repentance, and His warning was successful.
An example of an unconditional declaration of God is the Lord’s promise to David, “Your house and your kingdom will endure forever before me; your throne will be established forever” (2 Samuel 7:16). No conditions were stated or implied. No matter what David did or did not do, the word of the Lord would come to pass.