What about those kids who read complicated books early, does it even out at the end? I am truly curious.
My two have not evened out (yet) but that could be because they do really have gifted IQs (as much as you can tell in a 6 and 8 year old). DD started kindergarten with reading fluency well above the 99th percentile and she is still above the 99th percentile 2.5 years later. She reads a few grade levels ahead (she's 8 reading around a 6th-7th grade level). DS hasn't shown any sign of slowing down either. He has always been extremely good at decoding using phonics (started around his 4th birthday--I didn't try before that). I think he started to read shortly after his 106 GAI was calculated at age 3. I thought that was a little weird that he was reading well at age 4 with a solidly average IQ, although I also knew that he also wasn't particularly cooperative with the testing and it probably wasn't an accurate score.
Some kids enter kindergarten reading but are not gifted--they are probably somewhat bright but also have parents who work with them a lot. Those are the kids who probably "even out" within a couple years.
Anyway, I wouldn't over-analyze the scores too much at this point. His score is probably high enough that it's not going to fall out of the gifted range, but whether he's going to be a DYS scholar, it's too early to tell (IMO).