The only way we could end up with C over D is for political reasons.
The pollies aren't that dumb. Let's face it, within 30nm it's controlled airspace or it's not. This nonsense about the fine differences of C verses D is really just nitpicking codswallop.
If you want to invent an airspace type that allows you to swan, VFR, over the top of YSSY at 1500ft no-radio, then fine, call it E. But please stop this incessant C verses D argument.