Worried about what will happen to my disabled brother when my parents die?

I have only 1 sibling and he has aspergers syndrome. I was part of a large family however my other siblings died young. He is clever and has various university degrees and he has also done modelling as he is very handsome however his mental problems are quite severe. He doesn't really have any friends and is unable to behave and speak normally. He is very lonely and sadly probably always will be because he was born lacking the skills to commuincate and form relationships whether romantic or platonic. He acts like he doesn't want friends and often declines the few invitations he does have. At the moment he has two loving parents who he is the world to and he lives with them and is doing ok. I am very happy at the moment because I am in a fairly serious relatioship and have a wide circle of friends however despite my youth I spend many days worrying about what will happen when my brother dies. If he were downsyndrome of something it wouldn't be so bad because he would be happy in a home but with the condition he has I don't know what the options would be. I just don't want him being lonely when my parents die and wasting away in a house on his own. What are the different options for someone with these sort of problems when they no longer have a guardian? My boyfriend says he can't live with us when my parents die which is understandable however I would like to live near him and have myself and my children visit however there is only so much I can do and we are not close at all