What Jennifer told me when I interviewed was that they never over-accept the class at OHSU. After they finish interviews and reviewing all the people in the hold category, there will only be 100 offers of acceptance. Once a withdrawal occurs, they go straight down the alternate list accepting someone to fill that spot. She also said that at that point (april 2nd), only 60 acceptances had gone out so far and they had evaluated candidates who had interviewed up until mid-February. So, it seems likely to me that when they review everyone in the hold category, they will definitely make some outright acceptances because they will make enough offers to total 100 plus acceptances to replace the people who withdrew. I wouldn't be surprised if they offer 20 or more acceptances to people in the hold category.
Bottom line: Don't get bummed out now! I think you've all got a chance at getting accepted sooner than you think!