People started talking about sea thematic and I want to play "Sid Meter's Pirates!" again...
Anyway, you people sail in Sea of Eventualities too far from home and completely forgot about that we talking about RPG, not sailor simulator. Of course it could be nice to have all things which you described (except cannibalism, sorry guys but it's sounds cool only if you live in comfy modern house and sitting behind the screen while tip your fedora and drink sugar tea until first dock where you will be executed), but I think we will be have at best a different weather types with storms and sea monster encounters.
You see, hunger/thirst systems can be nice addition to the game, but you forget that these things need to be balanced and here things become more complicated than it seems on paper. Not to mention that if we want sink for money, like hunger/thirst system, we want also have decent source of money in every port. Because in another case player and his team will have stuck in city without money, supplies and water. Maybe hardcore gamers will say "Well it's the end of game, try new/load again", but it is not solution since we talking about not piss poor islands like it was in Sid Meter's Pirates, but about RPG where according to lore over9000 towns populated with people who can give you a job. IRL that problem had solution - find a job in port or deeper in mainland, but since it is impossible to create map in size of Daggerfall with modern graphics (or possible, but let's say VERY time and money consuming) for every fucking island and very hard to do in size of Arcanum - only way to gain gold is job in port.
And there come problems with NPC AI, because they can’t generate new well written quests (dream of every developer) so player is about to do tedious quests like in any MMO and do that ove9000 times. That problem can be solved by adding dungeon in every city, but dungeon in middle of big city looks like alien on KKK meeting prison in middle of Red-light district, not to mention that respawn of enemies should be lore wise, not like in MMO. Not to mention that all dungeons should be individual for every city, because it's not Oblivion or mods on BG - you can't copy&past same location over9000 times but with different angles. There also way to make loot in trash bins respawn so you can craft useful shit and sell it, like in Arcanum, but I don't think many people would like to running around map and gather garbage for hours with reward in small pile of gold.
I think balance problems with thirst/hunger system can be too much complicated for realisation such system in game + there a lot of other things which should be balanced and done better than in previous game.
P.S. I know my English sucks, but all I wanted to say that most likely hunger will be not implemented in game. Because many reasons.