The difference in those targets is that they're uncertain, and that that uncertainty compounds as you reach further into the future. I don't think the nanopass

The difference in those targets is that they're uncertain, and that that uncertainty compounds as you reach further into the future. I don't think the nanopass-in-reverse approach lends itself well to resolving uncertainty, because you'd start from the point of most uncertainty, which sort of begs the question a bit.