I can't now find where I mentioned it earlier but I wanted to expand on a thought about Black Sails as a tragedy. It's not so much about individual characters reaching particular endings. Rather, I think the central tragedy is that there is this fight - this war against the world, against civilization itself, which is the driver for everything Flint does and arguably the entire plot - that then doesn't take place. The story goes right up to the brink of this conflict, and by the end it's not just Flint raging alone against the world with whatever pirates can be persuaded to follow him, but it's Madi and the slave revolt and an entire people driven by what has been done to them and to their ancestors, it's something so much bigger than the individuals involved, with potentially world-changing consequences, history-changing consequences, an entire overturning of the colonising powers in the Americas.
And therein lies the tragedy, because we know the history, and we know that this story isn't just a Treasure Island prequel, it's interwoven with historical individuals as well and places itself in that context, and invites us to imagine what could have been while at the same time haunted by the spectre of how history actually plays out. The tragedy is that the war never happened. We know from the beginning that the war against civilization could never have been won in this story, but it still invites the imagining - what if, what if?
And so the audience is forced into the position of Silver, who is confronted with this vision of the future so ardently pursued and believed in by Madi and Flint, and cannot imagine it playing out. Silver, because he never believed in this fight to begin with and only knows that he will lose the ones he loves to it; us, because no matter how much we may believe in the cause, we know that they don't win, that there never was a slave uprising and pirate revolt that overturned the entire New World. Silver cannot bring that future about. All he can do is end the story.
Black Sails asks us to imagine, what if the treasure was not just a chest of gold, but an entire possible future that was killed and buried in the ground on a lost and forgotten island?