My take on cargo fire-
If you get the warning in the air- Do the Ecam actions- Land ASAP, advise the purser to inform you if there is any sign of heat on the floor (even if that means removing his/her shoes), or sign of smoke in the cabin. If the answer is "Yes"- Evacuate after landing.
After landing stop, and request from fire services if they can see any signs of smoke or fire.
If "Yes" - Evacuate.
If "No" continue to gate and air bridge while still keep Cabin crew on alert. You can always evacuate prior to parking.
Prior to parking inform the fire service NOT to open the holds until all passengers have disembarked.
Disembark all passengers, and your crew then allow the fire services to open the holds.
In the Singapore case-
the report said "
During the descent towards Bangkok a burning smell developed on board of the aircraft.
If it had been me that would have been indication enough to initiate an evacuation after landing.