bihira ang magkaroon ng friends na tatagal 'forever'. that being said, it's not impossible for some of your hs friends to be your friends beyond hs. however, it's inevitable for you and your friends to drift away from each other, because you're all going to different paths in college, and along the way building your identity and discovering who you really are. your friends will change as well and sometimes you might discover that who she was in high school might not be what she is right now, and you have nothing in common, apart from history. at that point you have to decide if you still want to be friends with her.
i only have one year left before i graduate from college, and to be honest i have lost touch with 90% of my high school friends. it's funny to see how much they have changed. granted, i'm not a people person and i dont have a large circle of friends, but i still meet up with my closest hs friends, but those happen rarely because we have conflicting schedules. we have facebook and YM, but it's really hard.