Honestly, it’s a ‘how long is a piece of string’ question and answer. I have an adult child with ASD (diagnosed as a child), and I have friends with ASD children diagnosed as children. While my child speaks eloquently, is academically able, in the workforce, professional job, has a social circle etc, my friends child lives in an 100% assisted living facility, completely non-verbal, non toilet trained and is dosed up to the eyeballs with antipsychotics merely to keep them manageable so they won’t harm themselves or others due to the levels of distress they suffer. Other friends have kids with ASD who fall in different places between this with ability. Unfortunately, we can’t use any terms to distinguish between such groups as you will have people with ASD who will come on and eloquently tell you they are every bit as worse off as the person in 100% assisted living, unable to talk or communicate at all, smearing their own shit everywhere at 25yo and how dare anyone say otherwise.
So, really no one here can tell you the future of your child, only their own experiences. My child with ASD (plus ADHD plus other things) struggled through primary and junior levels of high school. They were super bright but not in the way schools are set up. So funnily were not considered academically able until senior high school where they were able to take subjects that aligned with the way their brain worked. They were able to read at standard age, but had zero interest in doing so, and didn’t (doesn’t work well when schools are adamant kids should read, read, read). They still would never ever read for pleasure but can read, read well, and comprehend what they have read to an high ability, just choose not to (unless some challenging technical manual for something they are actually interested in). My child did a sought after challenging uni degree, where pretty much everyone else doing it also had diagnosed ASD🤣, and are able to perform well in an associated professional role. The key has been aligning interest and ability to study and work. If they were made to work in a job that held no interest to them and their brain was not aligned with they would likely either leave within hours after a massive meltdown or be fired within the day.
My child has hobbies/interests and fortunately or unfortunately, again pretty much everyone they know associated with these has ASD. So a wide social circle, and in fact socially they are busier than my NT kids, but it’s pretty much all people the same as them so they all fit in and consider each other as ‘typical/normal’. This, together with work means they don’t really have much exposure to a world that is not ND apart from family. The only deviation to that would be sport, which they are also involved in and they seem to be the only ND person. Honestly, I think they are only accepted by teammates due to their technical skill and the advantage it’s recognised that brings as they play competitively, if they were useless at it I doubt it would have worked out past tween years. Also helps that they don’t drink and are happy to be designated driver after drinks post game or social nights🤣.
My child is happy, but again, I believe a lot of that is because for the majority, they are pretty much able to function in a near total ASD world and as family we are fairly accommodating, but not to the point others are adversely impacted. The other thing that enables them to function, and I believe lead a good life, is medication, without which they are pretty fucked. The way we think of it though is no different to a diabetic requiring insulin, an epileptic requiring seizure meds etc, and would be like refusing glasses for someone with sight issues.