It's so hard to be 18 and suddenly have to choose "what you want to be when you grow up". I don't know a single person who is doing today, what they thought they'd be doing back when they were making choices at 18. I'm sure he'll be fine.
... and you're not done yet. You know what they say, a kid knows "everything" until they hit 19, and then suddenly they realize they don't know anything at all. He'll be leaning on you more and more, I bet. (It's amazing how smart parents become after their child hits 18... so I've been told!

)