Hello to anybody who takes the time to read this, and thank you in advance to anybody who considers responding. I would greatly appreciate some insight 
I'm 23, and my brother is 22. He has low functioning Autism, and is non-verbal. My parents are his main carers (49 and 51 years of age). They're fantastic with him. They've raised him to be a mild, playful, sociable and calm young man. Respectively, I partake in more of his care the older I get.
Lately, due to certain developments in the family, I've been worried about the next 10-20 years or so. I know that even 10 years can bring huge changes - employment, housing, relationships, a possible family of my own etc. I also know that my brother's needs and tastes will be subject to some changes and some "slowing down" as he ages (i.e. we're not getting any younger!). Even so, sometimes, I feel like I shouldn't be planning too far ahead with my life. I feel like my life will eventually need to be a devoted safety net to his needs, and I sometimes feel guilty for wanting to press ahead with so much personal ambition in my own direction. I don't believe my parents have encouraged me in my education to university level, and to pursue my career, only to drop it all and become a full time carer one day. And frankly, I wouldn't want to after so much self investment. Of course I'm willing to make compromises. I always want to be in my brother's life. I just fail to see how this is possible if I have my own 'full time' life and career; especially as it is likely I would NOT choose to have any respite care provisions for him (I don't disagree with respite outright, it's just not something my parents have ever wanted for him, and I respect this).
I know this is something which would be a highly appropriate family discussion. However, my dad isn't one for talking. My mum is what we affectionately deem as "old school", in that she'd simply tell me to be young, have a life, and not worry (which is easier said than done). I'm not an only child. I have a twin brother, but despite him having a very responsible job looking after vulnerable adults, and being fully aware of our home life, he can be fairly oblivious and selfish in his life sometimes (ironic, I know). He's known for being unreliable in family matters. This aside, he also works very long and antisocial hours, and I hardly get to speak to him.
I feel lost. The impact of this unavoidable outcome seems to be developing a wider black hole in my mind day after day now. I'm not asking for a timeline, because I know life doesn't work like that. I suppose I'm just looking for some sort of similar story, kindred spirit, or something to anchor me back down to earth, if at all possible.
Could somebody please offer me some perspective(s)?