What makes you say that? I personally feel that this is not the case. They've given pretty much all their acceptances in December and January and didn't even begin accepting people until November, so a good amount of the people they've accepted so far are the people that are likely to get acceptances elsewhere. It may be the case that they waitlist all of the future interviews because that's what they've done so far, but as awful as medical school admissions can be, I really don't think they would knowingly waste the time of hundreds of people interviewing into late April if they intend to reject all of them. I believe that they will eventually accept a lot of the 2016 waitlisters.