Voel,
By RNAV approaches do you mean RNP-AR approaches using the FMS and onboard nav systems of the aircraft to a standard of RNP 0.3? These are actually different to the current RNAV instrument approach using the GNSS/GPS that are common into most airfields in Oz.
In Oz we are about to start a major trial using RNP Approaches into Brisbane, Cairns, Coolangatta, Townsville, after RNP approach trials have been conducted at Canberra and also Queenstown in NZ.
At this stage the separation standards are the current standards. So approach radar in Oz uses 3nm, 1000ft, etc. Procedurally, you use your current procedural sep. standards for GPS/GNSS (which would be big in the terminal environment).
ICAO has yet to determine if special sep. standards can be applied to RNP 0.3.
Hope this helps.
Dick N Cider our guru on these sort of things in Brisbane might be able to explain in more detail. (Come in anytime now DnC).