I just joined a beta community that's been around for a long time, lots of the users are at 6,000 reputation, but because it's a Beta site, a Trusted User only needs 4,000 rep. What happens when this site eventually gets launched? Does everyone keep their privileges? Or do all these Trusted Users with moderator privileges get demoted to approving tag wiki edits?
All of the privilege levels will be re-adjusted to their normal levels and users will continue with what privileges their current reputation gives them in those adjusted privileges. So a user with 6,000 reputation would no longer have the trusted user, protect questions, and access to moderator tools privileges.