I need advice re: my older son and college and career choices. He's 16 and a sophomore in a competitive, academic magnet high school.

In a nutshell, he's not remotely suited for the kinds of careers he fantasizes about. Whether as a result of his Asperger's or just extreme immaturity, he's still coming up with things like biomedical engineer and other grandiose goals for which he is entirely unsuited. For one thing, he's a VERY unmotivated student. And his strengths unfortunately lie where mine did: literature, history, psychology. He struggles with math and the harder sciences (although he did very well in biology). To top all of that off, his PSAT scores seemed really mediocre to me but either the College Board has dramatically lowered their standards since I was in high school or they just send their shit to everyone, because he's getting mail from them telling him he's very qualified to take AP classes, blah blah. So to him, that's evidence that he's doing just great and biomedical engineering is within reach.

So I have a couple of questions. First, how can I get him to lower his sights a bit and be more realistic about the kinds of college majors and careers where he could succeed? And second, given that his strengths are in the liberal arts and soft sciences, are there ANY good careers out there for someone good in those areas but who doesn't particularly feel suited to a straight up office job? I fear he's going to be living in my basement until I die.