Remember that cargo smoke is detecting smoke, not fire. There is no cargo fire detection system. So at no time can you say whether or not you have cargo fire.
Therefore regardless of whether or not the cargo smoke warning stays on, you actually don't know whether or not you have a fire.
For me, I would keep normal electrical power with the apu, and close communication with the cabin crew. Any sign of actual smoke in the cabin then evacuate immediately. If not, then continue to gate or disembark by stairs, leaving the cargo doors closed until everyone is off.
Finally, i don't expect that the fire chief on the ground will be able to see much (unless they have thermal imaging camera... is that actually common equipment for airport fire crews?). The cargo ventilation system will be closed by your ecam actions, and the doors are all sealed. Even with a fire smoldering away in the cargo compartment, I don't expect there would be much smoke escaping for the fire chief to see.