I'm personally hoping that we will see national naval budgets in game that closely reflect reality. So we will see countries like the US, Germany and UK being 'easy', while countries like Spain, Italy and Austro-Hungary will be 'hard'. If this is the case, then countries like those in South America wouldn't really be very playable at all.
That being said, I am very much wanting minor nations to be represented in game. Selling ships to smaller countries and forming alliances with them would be cool, as well as seeing them build smaller navies and engage in wars with their neighbours, perhaps causing a diplomatic crisis.