Disappointing to see this question go unanswered after so many years. This is one of the very first concerns that I am having when considering teams and sharing. Seems like a core need for such a service/software.
@LucidHeart We have developed this for Business accounts, though I realize this level of account set up may be much larger than you need. Have you considered using shared folders with users instead? These will not be deleted when the user is removed by an admin.