I would really like to see the ability to use the older hull models for pre-dreadnoughts, ect in more modern designs. I think this would be really interesting as it would allow for more variety in late game and the mix of the old styles and new technology would be rather fun. I ask this because I have to admit I really like tumblehome hulls and would really like to keep using them in the late game!
If possible I would also be very interested in the ability to choose a nation for the campaign so you can play it out with a mix of starting budgets and resources, always fun to start off weak as the Chinese Empire and attempt to challange other world powers.