I don't know literature in this area, but I would assume that, yes, reading does even out at some point. What I mean is that at some point most people will read at 3rd grade level, or 8th grade level. It's just like all people sooner or later will learn multiplications. But I think the point of differentiation is that, while others learn to reach a 3rd grade reading level or math level, the kids who are already there should be learning something that they don't already know how to do. I just think the argument that "they will level out in a particular area" is irrelevant.
