Will be interesting to see how this plays out, looks great thus far. My question would be, how much control will the player have over the architectural style (and any resultant utilitarian (dis)advantages) of Campaign World structures and their progression from Rank 1 onward? If I stumble onto a partially ruined fort in a CW and renovate it, am I tied to the original architectural style or will I have some freedom to strategically customize my defensive structures? If halfway through a campaign my primary opponent shifts from squishy casters to heavy meat will I be able to adjust my defenses accordingly or am I locked in to decisions made early in the Spring? Will all Rank 3 Keeps look the same?
I'd love to see a "tech tree" for CW assets, specifically defensive structures. Player gets wide control of his defenses but with limited resources so he's forced to make tough decisions between, say, building a glacis or adding machicolations to his walls, or between square and round towers. Do you want to fill your walls with rubble and sand to help them withstand heavy artillery and battering or do you want taller walls with more favorable angles to increase enfilading fire? What about a moat or defensive foreworks? Certain choices lead to other options much like the Civ Tech Tree except that you can't research everything. If at some point, as in the scenario above, a guild is faced with the need to adapt their defenses to counter a new offensive strategy they can do so just like you can unlearn talents in many MMOs, once you've reallocated your building points appropriately you can finalize it and renovations begin. Could even add a "construction time" to the tech tree when re-allocating points so an owner could weigh the benefits of a renovation with the cost/time it would take to complete.
That would grant players maximum freedom without allowing for hooligan-shaped castles. You'd likely see cities and fortresses become more unique as campaigns progressed as well, each with its own set of strengths and weaknesses based on the decisions made by its' builder(s) just like one would in real life. It also adds structure to the timeline of progression so that a strongholds' defensibility keeps pace with players that, in theory, become more powerful as a Campaign progresses.