I've suggested they take a Dark Cloud meets Hamlet defense sort of concept for FC, I think that would be a rather interesting opportunity for FCs. GW2 also has some ideas that may be worth taking during that. Here you would make your own FC hamlet expanding territory, adding facilities, and then getting to protect it as well. Protection can be perhaps opted out but reduce in some sort of reward / rate, like you hire GC guards to take care of the hamlet (or another FC- which adds opportunity for other FC to see other hamlets, the system can just pull from the list "this place needs mercenaries" and another FC looking to do variety of hamlet content will get thrust into that area, even if they fail it might not impact the hiring FC, just the merc. FC's rewards). Adding onto this there then can be some NPC hamlets (like 1.0 hamlet defense was), also thinking of best ideas and systems from Aht Urhgan's siege, then also beast tribe strongholds where players can do assaults onto 'enemy' hamlets. FC can do FC vs FC content.

A strong opportunity to use the reputation system that FC has but doesn't really use currently. Now you could have players help build reputation both by their own and also group experience, this reputation unlocking new facilities and npcs that might exist within your hamlet.

While Island sanctuaries is for the solo player and casual the hamlet system would be for the group and more industrial focused.