I wish I could visit campus so badly, but i'm working overseas and it's a 24hr series of flights each way. At least they have off-campus interviews in person. I hate skype interviews with a passion!
I think you guys shouldn't worry if you can't make it to campus or a team exercise and have a good reason. The admissions committee seems to have a pretty good idea of who they want to admit and waitlist before the interview starts according to the interviews with Soojin Kwon. As with most things in the application cycle, the battle is won or lost before it is fought. If you bring the same great person to the interview that you portrayed in the application, i'd guess your chances are even better than the ~70% admission rate for people who have scored interviews.