Hi 2boys I see. I don't know what ABA school you viewed, but when I went to visit an ABA school, the headteacher strongly and I mean strongly recommend to us that if a child seems high functioning on the autistic spectrum, this would not be the right place for them.
Maybe part of the issue is that you have't found the right school for your DS to go to. I looked at 20 special schools and only two of those schools were the right fit for DS. But I remember the feeling you had when I viewed certain special schools.. the expectations of the students were lower, the older kids didn't seem to be improving as much or gotten worse actually (but who am I to tell).
But when you find that school, and you will, and you get that positive gut feeling about it. All you worries will disappear, trust me. No school is perfect and I don't think the special school, that DS is going to, put emphasis on academics. But If that's the case, I've decided that I'm going to work extra on academics with DS at home, I also have a friend who is a teacher so she can assist me. You can be the smartest person in the world, but if you can't communicate, then it's a waste. DS will be going to a school where the therapist and TA's are highly trained, he will be getting the appropriate support and like another poster had said, don't think of your DS in the future, think now. If you find that your DS is doing really well communication wise and is very academic in years to come, you can always move him back to mainstream or into another specialist school that is very academic.
Plus no, you don't need to spend thousands on a barrister. I did spend lots on reports and for the witnesses to come to tribunal. But a charity represented me and I won. So don't let that put you off.
You will find that school OP, even if you have to look out of borough, you will find it.
Good luck.