You might be interested in this older thread:
http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/162404/Re_Hyperlexia.html

As a 2-year-old reader with a son who was a 2-year-old reader, and someone who's spent lots of time reading hyperlexia and autism research... I believe the research isn't good enough to tell us parents what to expect for our particular children. Anything is possible.

Hyperlexia has maybe dozens of studies at most, mostly with tiny sample size. The hyperlexia studies don't even agree on a common definition of "hyperlexia."

If your child is doing great at age 7 (my son is about that age too for what it's worth) he'll probably keep doing well, surely? But it's more useful to look at kids individually than to rely on categories like autism and hyperlexia.

My interpretation when some of those papers say the other kids catch up is that there's a kind of plateau where reading skills are as good as it's useful for them to be, and at that point kids switch from "learning to read" to "reading to learn." This doesn't mean that hyperlexic kids regress, or that they can't also be good at "reading to learn," it's just that being advanced at reading stops distinguishing them once other kids make it up to the plateau too. At that point, other traits matter more than reading ability.

My son was also a 2-year-old fluent reader (1-year-old beginning reader), lots of social and sensory kind of issues, and he's doing very well now in 1st grade. He had a decoding-vs-comprehension gap for a while but in his case I think it was mostly because preschoolers don't understand the world. His comprehension is good now that he's older. He had an IQ test as part of a school assessment at age 3 and he was very good at the nonverbal (block design) part but had trouble with the verbal part. These days he's quite advanced in math as well as reading. He isn't a social butterfly but seems happy.

FWIW I was a 2-year-old reader carrying around toy letters all the time and the whole deal. I've had a lot of social trouble/disinterest throughout life, but was always very good at school-type things and went to a bunch of gifted enrichment stuff. As an adult I am a happy and well-adjusted person. But I expect my parents were pretty worried about me sometimes as a child and every part of school besides the academic work was an ordeal for me.