It will depend on your college experiences. If you can afford to do low-paying internships during your summer to get professional experience under your belt, I highly reccommend it. Get to know your professors. They are wonderful resources for future jobs. You never know when a professor might had heard of a job that you would be perfect for.
I graduated college two years ago and am struggling to find work. There are others who have never had to take an outside job. You're obviously willing to travel which is in your favor.
Yes, there are people who are crazy enough to date and even *gasp* marry us stage managers. You never know if you might end up with someone inside the biz or from a completely different field. I'm sure you'll make friends and get out to meet people.
Meeting people and getting along with people is so important to networking and finding future work. Use your years wisely. Work on projects that challenge you and help you to grow into a better stage manager. Work, work, work. Volunteer to work in the scene shop or costume shop or wherever. The more you know about how the theatre works, the better a stage manager you will be. Use your advisor to help you pick out suitable classes. I definitely reccommend taking an acting class, directing class, and design classes. These classes will help you understand what everyone in the theatre does and improve your communication between departments. These skills will help you find jobs.
I would definitely try to get going in the theatre department your first semester if possible. Right at the start of the semester, go to whoever is in charge of the stage managers for the theatre department and say that you would love to ASM. If the ASMs are already picked out, get yourself into shops and volunteer. Look for student productions you can SM. The more you can do in those short four years (they seem so long, but really they fly by!), the better prepared you will be to step out of school and find work and jobs.
Although I'm stressing work, don't forget to have fun! College is exciting and overwhelming. It's a good time to learn your breaking point and how to step back and say, "No." when your plate is too full. College SMing is very different than professional SMing. It was so much more stressful for me in college. I was jugling a full class load, SMing a mainstage show, working 30-35 hours a week, and in a committed relationship my junior and senior years. It was absolutely nuts. I once figured out how many "productive hours" I was using and how many "productive hours" we're supposed to have a week. (I believe it's 60-80?) I was WAY over the limit so it was no wonder there were nights I would come home and break down. Now, I'm doing one job. It's still exhausting and still long hours, but I'm not juggling nearly as much. So remember in the dark, scary times when you want to give up and go home, but still need to finish a lighting plot, that there were many more who came before you and many more that will come behind you. You are not alone and you will get through it.
*Whew* That turned out to be a lot of advice. Try not to worry so much about what the future is. College will turn your plans it upside down, and that's a good thing. Make the most out of your four years and your future will figure itself out from there.