There may be people that live close that could be called up to fill the interview spot at the last minute.
Usually it is best to give more notice than the night before. But I don't know your circumstances. So I will not pass judgement on your decision to not attend the interview.
Is it something that depends on a full complement of interviewees? Like an MMI interview, or is it more of a traditional interview? If it is an MMI, it gives a hole in the schedule that is difficult to fill. A more traditional,interview would be easier to miss you, but you will be wasting the time of any person that shows up to interview you. Interviews are a huge investment of time for those involved.
I hope everything is well for you, and you are considering this for good reasons (selected at #1 choice school), not bad ones (problems for yourself or family).