I wouldn't be talking to any child at this age about career options, especially one with special needs. The number of 12 year olds who really know what careers are out there and what will be out there in 6 years is incredibly small. A huge percentage of college freshman (age 18) don't know what they want, and that's why colleges don't even require them to declare a major until the end of sophomore year (age 20). I can't imagine why you would put that burden on a 12 year old with special needs.
I would work on his confidence and social skills, encouraging him to participate in activities and not worry so much about grades. If he has a variety of activities (courses, clubs, informal things with friends) that work on a little of everything, you'll be giving him tons of experiences that will benefit him even if you don't see immediate practical application. Not everything is about careers, right? A lot of it is about being the kind of person who can be in any sort of job and gain a career goal and career skills.
When he finishes high school, if he's not ready for a job or college, you can consider a transition program (sort of a gap year for special needs kids). I have friends whose kids have done this, and later they find their next path.
You won't have any idea what he's good at and what he loves (2 separate things which may or may not be the same thing) unless you give him space and freedom to explore to try different things. I went to Marshall's last week and tried on 2 pairs of jeans, 3 tops and a sweater. I only picked one thing. But it wasn't a waste trying on things and finding out what didn't fit and what didn't suit me. That's what coursework is like for kids. Something can be beneficial even if it's not career-based, and something career-oriented can be a bust. And kids can change their minds from 12 to 14 to 17 to 21....to 40. It's okay.
I wouldn't be considering his next step at least until he's 16. Give him some breathing room. No teen needs this stress.