i actually teach autistic children/adolescents (almost 7 years now), and i think i read the same article (people magazine?).
working with parents, i see their grief all the time. it's normal...all i can say (and I'm new here) is that for a parent who has a child that may not be what was expected...well, maybe it's not, but you can still have different hopes and dreams...theres a poem called Welcome to Holland and it's about what it feels like to have a child with disabilities, and your post made me think about it because it's exactly what you are thinking about...i'll try to find it and post it for you.
it's okay to have different hopes and dreams...and its okay to grieve...but i know my students with autism, they make progress and they have breakthroughs and they grow so much, so i do believe there is always hope.
hugs to you.