Feature that definitely will get in
Port battles will split into 3 levels next patch (eta mid may)
Regional deep water capitals (unless its a shallow water port) - will accept all ships
Normal deep water ports - will accept ships up to 4th rates
Shallow water - will accept ships up to brigs
Why stop there? Why not make drafts for ships like you have already, and let only certain ships with a deep enough Under Keel Clearance get in to port to dock/fight? This will make battles so much more intense and fun, since you need a much much MUCH wider spectrum of ships other than the 1st rates, the superfrigates and the mercs. This way you will Not only be able to play with the maximum of said ships, but ALL ships in the game will get a spot in the port battles. This has been mentioned multiple times, even by SteelSandwich(RIP DAS), but I can't take emphasys on it enough.