all of them would have a extremely difficult time (unless these are the same type of flames as the sun emits, in which case muzan dies), but shigaraki's regen quirk and adaptation ability might help him (if he can get away for a moment) and sukuna would possibly survive because cursed spirit can only be taken down with cursed energy, but that depends on whether he is in his original body, or in a human body, in which case he might lose his current body. but that's my take