What evidence supports the assumption that autism can not be cured?

I’m curious. I’ve always believed that autism can be corrected (perhaps cured is not the appropriate word). . . we just don’t have the means to do so yet. There has been tremendous success in mainstreaming high functioning autistic children and I think it is just a matter of time before the medical and educational community comes up with a better way to teach lower functioning children. However, many do not agree . . .