Man, I wish someone would have answered my question before it got buried. I'm legitimately curious.
Edit: "What exactly will (or can) you do with a degree in Japanese? I was under the impression that all you could truly do was teach english, and I've heard that doesn't have much room for advancement."
Interpreting and translation, Tourism, Teaching (Japanese or English at various levels), various government departments, business - particularly those that deal with Japanese clients and require knowledge of customs etc, journalism and the media, research (university lecturing), Diplomacy. My country's former prime minister is an ex-diplomat that has a degree in classical Chinese, just as an example that a language can really take you where ever you want to go. You are only limited, as they say, by your imagination. It also depends on your proficiency, of course.
I went to a great lecture last year where alumni talked about the paths they took. One graduated with a BA in Japanese, worked at a ski resort in Nagano or some where where she was scouted by a Japanese variety show, hosted that for a while, left Japan and started a company here that helps liaison between the Japanese and mining companies or something. Another guy took his Japanese skills and studied law at a Japanese university, and recently retired into teaching Japanese.
One of my university's Japanese senior lecturers is Australian. Her Japanese is pretty good, and she mainly teaches first years (as well as helping honours students with their Japanese thesis). University lecturing is more research focused though. Its definitely possible. Its also fairly competitive. I can understand your desire to teach at university though. High school kids are uninterested and even upon graduation have been taught only the basics. I'd much rather teach passionate people.