Honestly...nothing will really happen to these individuals. Unless it is a career that is specific to getting/practicing information, they will graduate and go into a career where they will be trained and provided with information.
I know, it sounds like the darker and more depressing side of things, but if it's English, Spanish, or some other class, that is unrelated to their future plans, than no, it probably won't have too negative of consquences. Now computer science, or accounting, or even some math (if going into a math field) maybe. However, it is what it is.
Something to keep in mind though, you're perpetuating the problem by witnessing it and saying/doing nothing. Whether it's confronting your friends or telling your professor's, you're violating the academic honesty policy by allowing that act to occur.
I know, this probably isn't going to be a popular answer, but in the end, think about it. It's kind of true.