Another Aspie here, trying to just put out some thoughts that may or may not have been adressed before.
First off, Autism is NOT a disability. It is only seen as one and feels like one because society doesn't (yet) have room for us.
That said, the first big thing is education; people, both autistic and neurotypical, need to know what autism is. Autistic people need to learn how non-verbal communications work, how to recognize and apply gestics and mimics as well as metaphors and figures of speech. It is possible for those of us with higher intelect - of which there are plenty - the others will at least know social subtext is there and how to communicate they can't handle it. On the other side, neurotypicals will learn how to communicate clearly and litterally - they will be taught how to see if someone has troubble catching subtext and how to make themselfs understandable to them, as well as understand that feelings worded with a neutral face are still as strong as those making a normal persons face show vivid expression. Here, too, there will be people more capable of adapting to the other side and people who will have a thougher time learning and eventually just having to admit they can't manage.
On the deep end of the autism spectrum there are also people who do not talk at all, even as adults. This, too, will be respected, and people will walk the extra mile to use whatever way of communicating works for that individual. Generally, I would hope that in an accepting and diverse world, people will be less seen as 'autistic' and 'neurotypical', but instead as 'individuals' with different social and intelectual capabilities.
On the subject of over sensitivity, I suppose there would also be some changes. I suppose there would be a larger variety to things like light switches that allow for gradually intensified light, air conditioners, fabrics etc, as well as more understanding of people that feel unwell in the presence of noises that someone may not even hear - like the screeching of a cat repelling garden tool that is supposed to be to high pitched for human ears, the noise of a fridge running or even those charging lights that keep me awake at night unless I throw a towel over them.
Clothing is another factor - I hate it with a passion, but I understand the social need of wearing clothes. Maybe, in regards to those younger or less high-functioning than I am, society might change to get used to seeing people that are not or incompletely dressed. Maybe being naked on the street, at least during the summer months, will be so common people no longer think 'sex' upon seeing exposed breasts or sexual organs. Given the still prevalent uproar about women breastfeeding in public, however, I suppose it will be more likely that fabric production and fashion go to great lenghts to produce a variety of clothing options to suit touch-sensitive autistics, like toe-socks, cat suits or robes, that make it possible for each of us to wear something moderately comfortable. Neurotypicals will accept, if not full or partial nudity, at least the fact that autistics put personal comfort over fashion.
Class sizes in schools would have to be much smaller - cramming 30 kids into one room is more than most of us can handle. In the same effect, there would probably be two kinds of parties - those loud, full ones in the disco, and smaller, more board game oriented ones that are quiet and more focussed on giving people a way to socialize indirectly over games rather than screaming at each other in front of big speakers. In working liefe, I would expect the trend going away from large, open cubicle offices to small, one desk per room ones - or offer both so employees who need it quiet can get their own closed offices and people who like company can be in a joined office space to work in a social environment.
I guess that freedom of choice would apply in a lot of places, not limited in a 'autistics get this, neurotypicals get that' sort of way, but in a 'choose what fits you' style. Just like today, you can get your happy meal with a doll or with a toy car - most people would let their gender decide, but they don't have to.
Generally I guess that a society with a higher amount of autistic people would be far more individualistic - mainstream would be more like a small river, and even neurotypicals might be more confident falling out of line, as just 'being yourself' is far less 'being weird' than it is today. This would also help people with other neurological differences, like people with down syndrom, borderline, depression or anxiety - if people are more aware of the fact that every brain works differently, there will be more social acceptance overall and being different will no longer be as big a stigma as it is today - perhaps it will even be seen as beneficiall, and teamwork will become more common as everyone brings their own strenghts to form a more capable group than one made of people that are all the same.
I suppose it is up to you as an author on weather or not you want to actually draw a distinct line between autistic people as an accepted minority and the majority of normal people (like ethnic minorities forming their own communities), or weather you want to paint a picture of a fully inclusive society where everyone gets along and intermingles (like men and women).
In the long run, I think the line would eventually disappear - autism is not an off and on, after all, there is a long gradient of all the colors eventually fading into white.
And just for the scope: I wasn't diagnosed as autistic until the age of 30. We can adapt really well if we try, and I have met many non-autistic people who can adapt to us just as perfectly.
