I like that idea! It stands to reason that if your entire fleet is obliterated, your HI wouldn’t be able to put up much of a resistance vs the enemy, so they’d win eventually thematically. In multiple player games, perhaps modify that rule so that it’s elimination-based. For example, player 1 destroys all of player 2’s ships. Player 2 is eliminated and can’t win anymore, but player 3 can still win by gathering the most gold or destroying player 1.
Makes me think back to Age of Empires and how a civilization would be eradicated from the game with a simple war! I’d definitely enjoy the option of going either for gold, a hybrid approach, or go all out with gunships and try to eliminate my opponents before they can satisfy their win conditions.