We live in FL and my daughter goes to Boarding School in MA. She definitely kept in touch with her "home" friends and has just enjoyed a summer of activities with her "old" friends. With Facebook and Twitter and Tumblr it is easier and easier for them to still feel involved in each other's lives.
There will be some inevitable emotional distance, but it was quickly overcome. Also this summer she kept in touch with her BS friends and they are scattered all over the US.
Friends stay friends no matter what!