Some things I'd like to see in the new RPG.
A Stephen You'll cover, and interior art if he accepts commissions for such.
Some art that is dark, shadowed (if in color), or shaded and inked to be eerie and ominous (if it's in black and white).
The main book should teach GMs how to run, and maybe even players how to play, political storylines. Additional books in the line should expand on the ideas here as needed.
The main book should contain a template for the creation of political adventures and storylines.
Plenty of plot hooks and storylines - those directly from the novels, and made up ones.
Useful rules for hunting and foraging that are not overly compicated or verbose. Being penniless and traveling seems pretty common in the books. Maybe we need a mechanic to allow for weakening when you don't have enough food, water, warmth, shelter, sleep, etc.
Population and demographics for nobles, land holders, knights, etc for the kingdoms.
Advice for the GM on using characters from the novels to drive events behind the scenes, so they can be included without being in harm's way, and without the PCs having to be involved as secondary characters to the novel story arc.
Common foods for feasts, inns, the lord's table on an ordinary day and when important guests are present, the common man's table, and the trail - like pg 89 in Feast for Crows paperback.
Details on the histories of the noble families, their internal politics, the ambitions of its members, current state of their immediate and long term plots and schemes, blood relation to and interpersonal/political relationship to the crown, relationships with other families, relationships with organizations, marriages and alliances, bastards and secrets, spies and information sources, spies for others within the family's household and landholdings, threats to their power and influence and wealth, resources (coin, land, its earnings nd natural resources, investments, favors owed, etc). Royal and other noble family's initiatives that they support, work against, and examples of how they go about it (recruit more men for the night's watch, refuse to lend money, poison, etc).
Encounter ideas/charts for the road, city, countryside/cross country, sea, beyond the wall, on the wall, maybe regions as well. - the north, casterly rock, etc.
Crime, the law, and punnishment - what happens to characters who get carried away with their swords?
Life and opportunities of hedge knights and robber knights
Lists of names to use for inns, ships, hedge knights, and other things you'll need to randomly come up with - first names, epithets, etc.
How the different types of magic work.
Rules for running (and being part of) a household at all levels - from the head of the family, to a small landholding, to being a relative with no landholdings.
Domain management, land yields, managing the domain and the family, or even the realm if you should win the game of thrones!
Rules and events for hosting and participating in tournaments. The hedge knight, and a game of thrones - maybe a supplment if necessary.
Troupe style play - teach GMs how to run games for players who want to play multiple characters in a family, or characters who reside in different regions - tyrion and jamie, brienne and kaitlyn, etc.
Creatures like the various dragons at different ages, dire wolves, the others, melisandre's shadow creature (if it's separate from the spell that controlled it) etc.
Spells - rituals to cast them, what training or faith is needed, etc.
Economics, Trade and mercantalism - pricing system, movement of goods, bartering, value of goods and services, etc. Tie it into farming and domain management as needed.
The black market - for players who want to profit from loot, war profiteering, smuggling, theft, etc.
Rules for crafting items of various quality, and for re-forging valaryian steel.
Capers - something similar for NPCs as they had for 1E Freedom City and Foes of Freedom.
Sections that describe life in the different landholdings - including regional maps, conflicts, dangers, etc - maybe a supplement if necessary. Basically, a grand gazeteer of the seven kingdoms. Think of books like the marklands, karameikos, etc. Should also include terrain features, noteworthy locations, local plots, schemes, politics and power structures. Bandits and other perils of the road and countryside. Generic inn, roadside tavern, etc.
Secondary products I'd like to see
Adventures like the dragonlance ones tied to the novel storylines.
Or maybe combo books - adventures/source material like locales tied to novels, and a book that elaborates on the novel like the LotR RPG books on fellowship and two towers, Mysteries of the Moonsea, Ptolus, etc.
Supplement - playing the war with Ned and Robert. The battles, the factions, shifting alliances, encounter locations, events - ways the PCs can play through and maybe even re-write the history. Something like Eberron's The Forge of War.
Supplement - playing during robert's reign. The in-between period where everything was festering under the surface, and the ground was being laid for future conflict. Another timeline expanding product like The Forge of War.
Supplement - the lands where Daenerys is.
Supplement - beyond the wall (or maybe include it in a gazeteer of the north)
Supplement - the high seas, naval battle, events, encounters and locations. Include rivers, smuggling, piracy, maybe also iron islands, and other sea centered regions.
The lands of Dorne and the Iron Islands.
Adventure supplements - or compilations of adventures - even as PDFs.