The plan has some leeway for outbound traffic but mentions nothing about arrivals getting into the mix.
the press release is a bit vague but the legal instrument is very specific
http://www.casa.gov.au/wcmswr/_asset...irservices.pdf
7. Airservices must ensure that, at any given time, the maximum number of aeroplanes in the circuit (including arriving and departing aeroplanes) for any 1 runway controlled by an ATC, is 6.
additional notes
8. For clause 7, an additional departure may be permitted at the discretion of the controlling ATC, having taken into account any relevant considerations relating to the interests of safety.
note 1 For clauses 7 and 8, the maximum number of aeroplanes in a circuit must not at any given time exceed 7 when 1 runway is used or 13 when 2 runways are used