I'm first tier, so they haven't exhausted it. Doesn't seem like there is nearly as much movement as years prior, but I suppose they could have done something different in the initial acceptance phase (e.g., accepted more outright than before, thereby leaving a smaller waiting list).
I've been in touch with the admissions office recently and was told that the class is officially matriculating August 15th, and that will also be the date when any remaining waitlisted applicants will be withdrawn.