I read 2 articles in the Guardian (I think!) last year which have come to mind and made me think of your daughter.
The first was about a couple with an autistic son, who bought some land from their local council and built a small residential housing development for around 20 adults with ASC and LDs. A bit like the Camphill Community Scheme but on a smaller level, run by people with a commited interest in keeping vulnerable adults safe.
The second was an article by (ex tory health minister) Savid Javid, talking about a scheme called Shared Lives. It's sort of like adult fostering for those with developmental disabilties, MH conditions, LDs and other conditions like dementias who need help with everyday living tasks.
Some service users live in their own homes, and visit the Shared Lives carer in their home/community an agreed number of times a week for support with socialising, finances, travelling, medical appointments, etc. Others have a full time live-in arrangement where they live in the SL carer's home like a lodger, and become part of their family (many service users have lived with their carer for 10/20/30 years!)
Javid was promoting the scheme as a kinder alternative to the loneliness of some residential homes and flats, and overall it seems to work out cheaper too, with lower rates of hospital admissions and illness, improvement in MH and overall happiness, community engagement, developing living skills, etc.
A good idea for vulnerable/non verbal adults who might not do well with the constant staff turnover in sheltered housing, and possible abuse/exploitation that comes from being alone with no one to oversee them.
There's an oil billionaire in Texas, USA who built a huge theme park for adults with DDs when he realised there was nothing available for his profoundly autistic daughter and her friends. I believe he's trying to start a housing Co operative too.
This might be the future of care for SEN adult children. Parents and relatives, along with other philanthropists building 'villages' for their kids and future generations of adults. With other neurodivergents perhaps getting involved too, where possible. There are a lot of autistic adults who do great advocacy work for the autism community and they could have a role here too.
I think it's going to take parents mobilising and forming huge networks together to get things done, because housing and caring about the most vulnerable will never be an issue that politicians can be trusted on. It's not a vote winner for them.
The thought of your child being supported by parents of SEN kids themselves as they age, like a huge community scheme, seems much better and kinder (though I appreciate there are some great residential placements, they're becoming increasingly harder to find/fund)