If you're about to start undergraduate, then you've obviously already chosen where you're going. What school will you be attending?
The traditional logic you're going to here on this forum is that you should study anything other than aviation, and that you should, in fact, not pursue aviation as a career. Most of these folks are angry and bitter, but consider that they used to be in your shoes. There was a period of time when they were just as bullish on this career as anyone, but were likely screwed at some point or another.
Also consider that there are people that have been ridden much harder than this angry, bitter people, and still find ways to enjoy their career.
Consider both of these positions as you move forward.
As far as WHAT to do study, the landscape on that issue is fluid. If your eventual goal is to fly for an airline, an undergraduate degree in aviation may be beneficial. It reduces the number of hours you need to be hired by a regional airline, and you can get student loans for your training.
If student loans are something you need in order to fund your education, consider very carefully that if you are able to get federal student loans for flight training you do through an undergraduate program, you may be able to get yourself on an income based repayment program. If you are, this could be huge. As an example, the Pay As You Earn program determines your monthly payments based on how much you make every month, and may allow you the flexibility to take low paying jobs to start your career without having a large debt burden on a monthly basis. This is, in my view, hugely important.
That being said, I went to Western Michigan in the fall of 2001 to study aviation, and walked out in 2005 with a degree in philosophy. I'm still working at an airline, and I've had no roadblocks in my career that were induced by my choice of undergraduate education.
Or said another way, it doesn't matter whether you study aviation or not, your success will come based on how hard you work, how well you network, and how personable you are.