This seems to be one of the major bottlenecks for new civs. Many regional influencers were thassalocracies, and yet the developers seem to be keeping naval additions to a minimum in expansions (Indonesia, Netherlands, Maori, Phoenicia). Assuming Portugal is inevitable and the devs don't release a massive naval expansion, there are not many slots left for naval civs. Maybe only one. So I want to figure out what that last naval civ could be. Only new civs included here. So no Denmark. No Byzantium. And I'm also leaving out Italy/Venice just to give the other civs a chance (and because Italy is a really complicated issue generally).