It seems that entering college or university as a musician makes it easy to decide one's major: music, as either a performer or composer (few undergrad programs have theory as part of their bachelor program). At the end of four years (or possibly five, depending on the program) you'll be bestowed with a degree that indicates you play a certain instrument or, that you compose music. Along the way you've learned much about music theory, history, perhaps some elective courses in music technology and taken part in some ensembles. You've undoubtedly learned, but now what do you do? Of course, that all depends on some of the questions you may have asked yourself along the way, (in part 1) and perhaps steps you've taken to achieve those things. But at the end of the day, in some ways, you're back to where you started before you entered school - you came in with your guitar (or clarinet, etc.) and now you're leaving with it; better for having studied of course, but what can this degree do for you?
If you plan to teach - not very much, graduate school is in your future. If you plan to try and get your band signed, go on the road and all that stuff, labels usually aren't very interested or impressed with diplomas. Many undergraduate students in music find themselves wondering what to do as they come close to finishing their degrees, and if the answer doesn't involve more schooling, it sometimes turns into a crisis situation. Again, it all depends on the type of school and program you've entered - if you've completed a tech program in engineering there might very well be a placement program for graduates. What I'm speaking about is the performance degree.
This leads me to recommend something I have seen a few undergraduate students do when they get to this point - something for which you could plan ahead before a crisis occurs: become a music minor, and major in something else. By doing so, you get almost all of the music education you would as a major PLUS training in an area that could help you find a job to support you as you pursue a music career, in whatever capacity.
A combination I often see is majoring in computer science with a minor in music performance. With the tech market still wide open, the chances of getting a job are much better than, say, getting signed to Sony at the moment. By choosing to minor in music, you will still take all of the core classes and ensembles - the main difference is usually in the amount of contact hours you have with private lessons, as well as a smaller recital requirement. This way you get the best of both worlds: the music training you are looking for, and a diploma with which you can actually do something. Immediately upon graduating with a Bachelor's degree, you have employment opportunities that a performance major could only dream of. I know it might seem hard to make this choice, especially since you've been gearing yourself up for your Berklee audition and are dreaming about days and nights spent practicing and jamming with your friends. But, try to see yourself four years from now; what's your next move? Success in the music industry, however that may be measured, has very little to do with actual talent and ability. In many ways, your success sometimes depends on the things you don't do, and the rest is just being in the right place at the right time (but you can take measures to be in the right place...)
So, to summarize, it's possible to receive the music education you've been dreaming about and at the same time, receive training in other areas, making you all the more marketable. I've seen many undergrads take business classes with the idea it will help them both as performers (contracts, etc.) or possibly as band managers. There is also a tech/music combo that makes a musician invaluable to a recording studio - there are so many combinations and possibilities. Just beware of the performance degree if you are a music major - it might very well be it's just the first step on your way to an orchestral career, but if popular music is the field in which you're most interested, take advantage of every opportunity university has to offer.
Most importantly, take advantage of the counselors the university provides. They are the ones that can best help you plan your academic career, and make suggestions if you decide to make changes along the way.