Massive spoiler for Insomnia/Dark Tower

In Insomnia there is this mention about Patrick Danville: “Clotho, smiling and clearly relieved: [Yes. Can't you feel it? Eighteen years from now, just before his death, the boy is going to save the lives of two men who would otherwise die... and one of those men must not die, if the balance between the Random and the Purpose is to be maintained.]”

But Patrick does not die at the end of the Dark Tower. I am confused as to what the prophesy in Insomnia means. Thoughts?