^^^ Don't agree. I will is a focus on the intent.

It's fine to say "I am" (writing a best seller) for the thing you're working on
But it always needs an eye to the future. "It will" (be a best seller) if you're going to visualise your place in the future.

The illustration in the original post is "each of my books will be on the best seller lists."
They have yet to be written. LOA wouldn't be appropriate for work yet to be done.
It would be a pretence to imagine they already are!


...