@ElitePinecone
The normal keeps change to what function we decide to make them have for example the espionage one will look like this.

Commerce

Miltary Might

Though you're right that beyond changing their functions they probably won't be to be customized beyond that, but I agree that the main stronghold will be customizable and have the ability to change many thing's but the full extent isn't known though they did tak about it in the crafting and customization podcast.
Anyway the normal keeps are bullheads that allow us access to the environment and more access to that area, once we establish a keep we can use our agent's to do various thing's like open the west gate near Velun, get Dagana to cap poisons to get more coin, rebuild the colosus.
Editing


This is from a recent article that gives more information on keeps.
Keeps form the centre of the game’s multiple, vast regions, and play a role similar to synchronisation points in Assassin’s Creed – capture one, and you’ll unlock quests. The more Inquisition agents dedicated to a keep, the more you can do. Fifty agents might rebuild a fallen colossus, for instance, boosting troop morale in the event of an invasion. Or you could send 10 agents to build a mine on top of a sulphur pit to shore up revenues.
http://m.officialpla...ries-fight-back