Of course. Everyone that has graduated from high school or left a group that has been together for a while has felt the same way. You still want to keep in touch with the people you've spent the last four years with - and some even longer from elementary and middle school. You'll go to college and meet a ton of new people. Everyone on your hall freshman year will be your best friend, I can almost guarantee it. Just about all of the people I know at school now, I either know from my hall freshman year or have met through them.
You'll still be seeing your high school friends over breaks, though, right? Unfortunately for me, we moved a month after I graduated high school, but my closest friends, I've kept in touch with on AIM and talk to them on a daily basis for the most part.
Either way, once you get to school in the fall, you won't forget about your old friends, but you'll meet a ton of new people and have new adventures, experiences, whatever.