>>1831620Mio is that type of girl who is going to wrestle with what she's "obligated" and told to do (especially in Japanese culture), and what she actually wants to do. English literature is not a bad guess since she likes writing lyrics. She knows a lot about bands though, so I wouldn't be surprised if she picked up history or something.
Your guesses with Yui and Mugi are shoeins for sure (maybe Mugi would do some sort of International Studies major because she likes to travel). Mugi will definitely move on to graduate school and get a really good education or work for her family's business.
Ritsu was pretty proactive and lets not forget, the leader of Afternoon Tea Time. While music isn't impossible for any of the K-ON's (especially Ritsu, since she'd need something to keep herself motivated), I think Philosophy would bore the living shit out of her. I honestly see Ritsu as the most bright and having the most potential of all the K-ON characters for a successful future. (except maybe for Azusa, who I believe will just get married. She cares *too much* about whats around her to get ahead in life.)
I can see Ritsu being a lazy political science student and really cleaning up her act (as in, learning some self-discipline and really doing her work) around Junior Year sometime after a brush with failure. She's been living on the high school hype for a while, but when she actually considers what she wants to do, I think she'll turn to a more professional decision over music AFTER all of her other friends get ahead of her in their fields and it seems unlikely she can play music for a living.
I think all of the characters would take a professional music opportunity if they could do, except Mugi (Especially if she's an only child.)
