Talltrees,
I did not read the whole thread, just your OP, but I have a son who has autism. He is 16 years old, and while he has huge strengths and is currently working with the custodial staff at the elementary school where I teach, he is considered on the severe end of the spectrum. He will never live alone, drive, or be able to manage his own finances.
I went through everything you described in your OP with family members.
My son has been an amazing force in my life. He is tenacious, despite obstacles. He is loving and caring, despite the experts claiming he is not capable of such. He is an excellent problem solver and thinker, despite IQ scores that on paper would indicate a profoundly low IQ. He blows my mind and warms my heart. I am lucky to get to raise him.
My son has taught me more about life than I can ever hope to teach him.
PM me if I can support you in any way on your journey with your son. Much love to you, mama...