Future music theory teacher?

I am currently a piano performance and pedagogy major and realized how much I love writing and history. In short, I would love teach music theory one day. Does this mean I have to switch to be a music education major??

You don’t have to switch. Ultimately, if you want a job teaching music theory at a high school, you’ll need a BSEd (Music Ed degree) but you’ll also have to teach either band or chorus. If you don’t want to do that, you’re better off staying with your BA, then earning an MM in Piano Pedagogy or MA in Music Theory and Composition, and teaching in a Community College. You’ll get to teach more Theory that way. http://www.music.pitt.edu/graduate/degrees.html#composition Here is the sort of Master’s degree you’ll want to pursue.