An an ex-Navy guy and an ex-hotel employee, I'm amazed at how well this went. Imagine getting everyone evacuated at 3 a.m. when people are asleep with their doors locked, and getting such a large fire out in less than 20 minutes.
I have seen some footage of several cabins, and it's clear the sprinklers did go off. Why aren't there sprinklers on the balconies? Probably a concern about them freezing in really cold weather. I'll bet they install them now.
If all ships were non-smoking (which, I would guess they will be eventually), there would not be any decrease in cruising, or I miss my bet big time. That's the cry of restaurants when a city passes a non-smoking ordinance, and it hasn't happened yet. Smoking is a dying habit.
Costa non-smoking? All those Italians not smoking? That's hard to believe, but I haven't paid any attention to them, so maybe it's true. Call me skeptical.
Edit: OK, call me more than skeptical. Every bit of research I have done shows that Costa is not only not "non-smoking," but probably smokier, on average, than most other lines, due to a high European concentration.
More edit: If I were putting this event in a novel, I would write this as a deliberately set fire, with the sprinkler and alarm in the cabin tampered with. But the most flammable item outside any cabin is, of course, the paint on the ship.