The decision to Land as soon as possible vs Land as soon as practicable, is why the Captain gets the big bucks.
But the bottom line from my POV is that it in virtually all cases of a fire on board it would be impossible to be absolutely sure that the emergency is over.
The best and only course of action is to get on the ground. The degree of urgency will be dictated by the circumstances, but IMO in every case the landing should be done in such a manner as to not accrue unnecessary extra time in the air.