I'm not "in the know" any more than you are probably, but I am in sort of a similar situation. I am on five waitlists, and I'm very interested in some of these schools, but I think my chances (and yours as well) are pretty good. Looking at statistics from various schools I applied to, my general impression is that many MD/PhD programs wind up admitting up to half of the students they interview, even though their class size may only be 1/4 of the size of their interview pool. But at this point in the game, schools can't extend too many offers and are just accepting their first batch of applicants, since theoretically all of those students could accept the offers (and schools won't know whether they do accept until the end of April when students are forced to release multiple offers). At the end of April, I think there will be quite a bit of activity and schools will probably accept another batch of applicants.
So if a school interviews 40 people for 10 spots in a program, before April they may only accept 12 people to be safe. But after applicants are forced to release multiple acceptances, the school might have to extend another 8 spots to replace people they lost. Some schools openly post the number of students they interview and accept on their website, and by comparing those numbers to their actual class size, you can usually see that there is significant movement off the waitlist.