I have an animal science degree (pre-vet) with an equine emphasis from a major university. I rode with IHSA, took classes on equine industry, equine evaluation, equine production, behavior and training, etc etc. I've been teaching/training full time for about 6 years now and while I absolutely loved my college years, quite honestly, my degree hasn't helped me out a whole lot. Sure, it's crucial to be able to evaluate the conformation of a horse but you don't need a degree to do it. The things that I use in my job are things that you need to learn with hands on experience and time in the field. I have a reputation as a trainer because people bring me horses to ride and they leave happy, healthy, and more rideable horses. I have a reputation as an instructor because people bring me their kids and they learn how to ride. Success in the show ring (for myself, my horses, and my kids) doesn't hurt either... Do you need a degree to do this? Nope. For me it's just icing on the cake. I know quite a few very respectable and very successful people in the industry with no degrees.
I think in this day and age though a degree is very important. I'm glad you're definitely going to college. It's especially important to have a back up plan when your life and dream is horses. You never know what will happen in this industry. What I think is really lacking in a lot of really successful trainers is business skills. Trainers/instructors/BMs/BOs use business every single day: management, law, insurance, finance, investments, accounting, advertising, different computer programs, I could go on and on. If you REEEAALLY want to work in the industry, my suggestion would be to get a degree in some kind of business and spend your summers working your butt off as a working student with a reputable trainer who is willing to teach you everything she knows and has a sizable network of people who she can hook you up with for a job after graduation.
Sorry, this is kind of long. :) But quite honestly if someone came up to me looking to be hired I would care less if they had an equine degree, or any degree at all. All I need to know is can they ride, can they teach, and are they willing to work hard.