The Army has started to enforce the "privileged and practicing" part of this a little more strictly in recent years, sort of, kind of, almost, not really. That is, they actually are requiring people to maintain privileges (a departure from previous policy), but the requirements to maintain those privileges are ridiculous. For my MTF and specialty, the minimum requirement to be privileged was to practice for no less than 12 hours per year. I say again, TWELVE HOURS A YEAR. That will vary between MTFs, but even if the requirement is tripled, it's still absurdly low.
If you're headed out to BN or BD surgeon land, then I believe part of the MOA between MEDCOM and FORSCOM is that a provider be given sufficient time to maintain his privileges in his specialty (and not just the operational AOC). That's not very much consolation if you're hoping to keep up your clinical skills, but it should be sufficient to make sure you're paid.