Everything you could possible want to know about being wait listed is discussed on this thread:
http://talk.collegeconfidential.com/prep-school-admissions/1300302-the-wait-list-p1.html
(Start with posts #2507/8 on page 126.)
No one can tell you what you (or anyone’s) chances of getting off any WL are, but this year is not a normal year, so sit tight.