As of 4.3, App Ops is a hidden feature and is not an officially supported part of Android (it currently requires a third-party app to access). This means that as developers we should not need to concern ourselves with how this affects our apps (at least not yet). I imagine if/when this feature is unhidden, Google will have convenient APIs for gracefully handling different permission states.
Until then, if you still feel the need to account for permissions at runtime, I suggest you see this answer