It's very much a question of "how long is a piece of string" I suppose but I can honestly say having my son accepted to a SEND school was the greatest thing to happen to him. And our family actually, they have been incredible with him.
He can learn in a suitable environment and he can make friends with children who have similar abilities and everything from visuals, low lighting, the ways they teach are all adapted to children with send to reach their full potential.
I think thriving not surviving at school age is more beneficial than anything else you can give a child with send.
I also think in an environment with others who need to have basic life skills that we take for granted with typical children that is only a positive.
I doubt my son will ever live independently, he's 7 and desperate for independence already for things he's just unsafe to do.
It does crush me, knowing that at best semi independent living with support staff is what his future holds but he has very specific interests that could potentially lead to employment, if he continues to flourish.
When my wee fella went to mainstream he was barely verbal and just attacked everyone constantly, now he speaks in full sentences and is improving with things such as peer relationships, his diet including foods that aren't just beige and also working on using the toilet with now only minimal support.
I'm a huge advocate for SEND schools and I've a few pals who's DC attended primary SEN and then went to mainstream secondary school or specialist college placements.
Worrying about the future is hell on earth when your child doesn't present as you'd expect from a similarly aged more able child and you worry about everything possible. If you can try to break down what is worth worrying about and what can go in the "cross that bridge when we get there" worry pile, it apparently really does help.
Good luck both of you with your journey x