After listening to the podcast and thinking about how far we are from Neo-UCS and possibly Man'o'War, I was thinking about how there doesn't seem to be much action on the fantasy naval wargame front. Obviously a diverse setting like classical Warhammer Fantasy or Uncharted Seas would seem a slamdunk, but there is one Fantasy setting that seems crying out for such a game. A Song of Ice and Fire/Game of Thrones is crying out for a system.
I would go for the book licence since a) probably cheaper, b) more battles and fleets, c) you can include stuff from earlier in the setting. It seems to have worked for CMON for their massed strategy game.
The advantage of the setting is that GRRM's world is mostly quite low fantasy allowing the game to be a test bed for a decent medieval game that can have magical elements tacked on, be it dragons, kraken, or wizards. You can really play up Euron's madness in contrast.
I would imagine the fleets being the impressive Royal fleet, with access to a couple of wildfire kamikaze ships, Stannis' stormlands fleet with an effective core of anti-pirate galleys and mercenaries, the elite and well built Lannister fleet, the impressive and effective Redwyne fleet with excellent scouting, three different possible Ironborn fleets of the Iron fleet of warships, the longship raiders, and Euron's magical fleet summoning kraken, the small and hardy Night's Watch fleet out of East Watch, the new Manderly fleet out of White Harbour, the Seagard defensive fleets, and Aurane Waters pirates out of the Step Stones. You could add on some Essos stuff if the game caught on, with mercenaries, the effective massed produced Bravos boats, the slave ships out of Slavers bay, Volantene fleets with Red Priest support. You could differentiate by Galleys vs. Sailing vessels, warships vs. longships and equipment of siege weaponry. Then something like Fantasy Flight systems with upgrade cards to represent certain commanders like Euron, Stannis or Victarion, or characters like Moqorro could give them that sense of ownership.