I fly an AONEx twice a year and have not had any difficulty getting A inventory for up to 2 pax on those routes that still offer first class. I've even requested QF, BA and CX to make an additional A class seat available from time to time without difficulty - it usually takes 24 hours for the request to be confirmed.

The routes that still have first class are decreasing though - long haul routing through MEL, SYD, SIN, HKG, NRT, LHR, JFK, ORD, SFO and LAX will maximise your first class chances.