According to the DSM autism is a lifelong condition. Ergo, children do NOT grow out of it.
SOME people absolutely have the ability to cover the difficulties somewhat as they grow older, and some people are misdiagnosed (have never met anyone mind you, although there was some discussion at University- studying for an MA in Autism alongside having 2 children with ASD, one in assessment and being assessed myself so reckon I know a little- about very early diagnosis being accompanied by a slight risk of misdiagnosis but being worth it in the long run as the children will still need help.
But you either have autism or you don't.
DS1 was diagnosed as having boderline AD years ago, he actually at age 13 has to attend a specialist school unit for people with Aspergers / HFA, he has grown INTO it if anything: and whilst ds3 has always been clearly disabled, the autism has become more obvious as the root of his issues as he ages.
Research is important but nobody is doing research into the great many services that autistic people miss out on (alongside other disabled people, I know)- actually considered doing something similar for my MA Dissertation and was gently warned off (doing parental reports of empathic ability instead).
Also- there is a lot of apparent links between people with very high functioning autism /AS who receive no long term support and other conditions such as depression, anorexia etc that we CAN help people avoid- articles like this have to be very carefully produced as they can support cuts to provision, yet cause lives that held promise to be destroyed long term and cost just as much in terms of long term psych support, unemployment support, marital breakdown.