Go for Economics. Flexible degree, very high ceiling as far as earnings go. As far as careers, there is no career that mixes well with fighting. Fighting is a career, so it's like saying what other full time job should I get that goes well with my current full time job. Personally I would say teaching is a good fallback. Get a degree in whatever you want, then add a teaching cert to it. You work normal hours and can get your roadwork before school, your gym time after, and a good hard training camp in the summer. If boxing doesn't work out you can still make decent pay, maybe coach the running team or something. Could even do a little side career as a club fighter if world titles don't work out. Just don't teach elementary, they have a ton of extra wok outside the classroom. Get an Econ degree, you can teach Social Studies, become a consultant (awesome career), go to law school or grad school, public office, etc. Lots of places will hire you entry level with that kind of degree. And as far as boxing, maybe Economics would position you for a spot with a television network or promotion company.
Thanks alot bro, its true that economics offers lots of advantages with its variety but i just think its job prospects are kinda weak compared to accounting, finance, management, badmin etc. It's interesting you mentioned teaching as i have always been fond of that job as well. I think in canada all you need is a masters in order to teach in college.