[st3fan]

tl;dr: The scenario described by the OP is now less likely to occur. Since October, individual Dropbox users are encouraged to create separate accounts when invited to a Team and warned that Teams admins will have control over the account.

I am going to be blunt here and just say it: the 'Team admins will have control over the account' part is completely stupid and not well thought through.

Becoming part of a team should be about sharing data. Not about handing over accounts.