I read somewhere (or watched, can’t remember) but I think people differ on this. Some say 20 years, some say 100. No idea!
I stumbled upon this vid a while back, I assume it’s fairly accurate as to the bow sections future. There’s no time limit, but if the upper decks survive another 50 years I’d be surprised. As far as how much is consumed daily, I forget the exact number, but Ballard had an estimate that was quite a large amount.