That may be the case, but if that is the case, then we are almost certainly not competing for the playoffs because that means Winston and Hill were both bad enough to be supplanted by a rookie.
Not saying it can't happen - just that I honestly hope it doesn't - at least not next season.
I think Book ends up (if he makes the roster) as the 3 and that Hill possibly has his "joker" role slightly reduced to protect him as the 2.
I think Payton want Harris to fill the "joker" role, more like a Tyreek Hill. So Hill may see his gadget plays reduced anyway.
I believe if Book shows any potential in camp and preseason - and shows that the game isn't too fast for him, then Sean will try to work him into the future plans.
I've watched several of the highlight videos and what I see is a guy with a lot of poise and I'm drawn to his footwork. It looks really good in the pocket - and as Bill Walsh proved with Joe Montana and Steve Young, guys with good footwork can do amazing things in the right system.