White Walkers would be end game threat and lot of fantasy units are done awesome in Warhammer 2 ( Dragons, Mamoths, Giants, zombies so I don't doubt they can be well implemented. I would use similar campaign types like in 1st Medieval ( Start of War of the Five Kings and 1 or 2 later starting Campaigns) There is also interesting 'A Song of Ice and Fire: Tabletop Miniatures Game' by Cmon that shows possible variety in factions, regarding design. There is question if it would be by HBO or book licence, and how to continue after the War of Five Kings, would map consist of only Westeros or would it go all the way to Qarthor or Vaes Dothrak which in my opinion would dilute the action. In my opinion Naval combat would need to be added. That can be only done as separate game, since modding is limited, and from experience bunch of mods are discontinued in Med2 or Attila. Gameplay additions in 3K ( character focused) seem to fit the setting, especially when imagined combined with discontinued Seven Kingdoms mod. On 2 July 2012, Creative Assembly announced Total War: Rome II with a live-action trailer that features different scenes with the theme How far will you go for.

2K A Total War Saga: Thrones of Britannia.

844 A Total War Saga: Fall of the Samurai.

Game of thrones total war rome 2