There are a lot of ways to go from this but.. I 'feel' that this is one of those few FC specific contents to progress on so if they did anything to it hopefully they could add something else.
Like I've flitted the idea before that FC get what amounts to 'island sanctuary' but industrial / for FC, like in the vision of a Hamlet. Something really old players might know well from Hamlet Defense (way back in 1.0). Also for those who've played it, thinking akin to Dark Cloud city building. Here you'd utilize the reputation tab to far greater effect as players who are out and about add small amounts of reputation for the FC (perhaps like the wearing tabards gains you reputation like concept in WoW). Gaining reputation helping unlock NPCs, facilities, and services for your hamlet. With many many layers of progression, and newly added content- it would ideally take FC a very long time to consider themselves nearly complete. For helpful functionality if there was a shop or something you really wanted, but your FC can't or wont build it because they have another shop they prefer- you can visit other FC's hamlets (this is to promote choices, and reduce the implication of not mastering every single option, for each individual FC but also a bit of interactivity between FC/players). Adding hamlet defense and stronghold assault content as well. Other idea was airship related...
Then I think the relatively... Um.. visually non-compelling.. Systems? I mean it's mostly a bunch of menus lol. Is moving the submarine / airship to player garrisons (/NOT/ housing).
That said I could also imagine the workshops get moved into the hamlet, which could be really fun to get to see your airships docked / floating in the distance (and submarine). So it doesn't have to be extracted from the FC. I wonder if there is some sort of system SE could think of to help make some of the content a bit more.. pre-group organized? Like if everyone pitches in to have an airship get a mount, but then only one person gets that mount. I feel maybe that system exists is 'fine'.. but also might there be a more sanitized system that works just as well? I'd love to sit down and try to hash out a system that operates more consistently with the group nature in mind. Personally this has never came back to bite me since my FC is cool, but I can only imagine the unnecessary nuisance that exists for some FC because of course they'll let you help build it but they're not going to share the rewards of the group effort until all their friends get it first (or never).