I hear waitlist movement is fairly good. WillOfTheSon or any admitted student currently can probably share more insight to the exact class make up. But in the past SDN threads it usually seems like its pretty fluid. AMCAS choose your medical school deadlines are coming up. So on each step there will probably be some spots open up. Then at the final decision day sometime in April or May there will be more movement. Lots of trickling in over the summer as well. I will say admissions can vary year to year even before COVID some years have better yield than others, so we may have a good amount this year.
I wish everyone luck I know it can be crushing like you said. I know OU doesn't accept updates after deferrals, though I'm not sure their policy on letters of intent/interest and updates after waitlisting. I would check into it, and to quote what another user posted in previous years, be an advocate for yourself whenever you can (provided its appropriate). Lastly, I know its cliché, but before the A last Wednesday I was struggling a lot with how this cycle was turning out, especially as an older applicant who's going to be over 30 when I graduate. Remember to take care of yourselves and guard your self confidence in your abilities. I'm not sure how helpful any of this is but I do hope for the best for you guys.