Its already been mentioned that we'll be awarded decorations, medals and titles throughout our career. We'll build relations with factions like the Empire and Stahlmarkians and be able to call in what amount to favours. What else would people like to see in the metagame? It could be interesting if the player developed certain traits or developed a reputation for a certain style of governing. If the player has a history of unearthing Eldritch horrors they might find the Anti-Paranormal Investigation Squadron keep a closer eye on them. If the player has always been nice to the Stahlmarkians they might have visits from Stahlmarkian traders more often. The problem with this however is that it might hinder the player's ability to try something different. If they want to try being nice to Stahlmark it might be tough if they barely ever encounter them, because of past grievances. I'd be interested to hear the opinions of others on this subject.
Maybe you would have an option to go under a pseudonym? Gamewise, keeping decorations but removing any reputatition or ability to call favours.
I think it would be cool to have personal mansions that you spend medals / achievements to decorate. That way you have a building in game that reflects your past glory and how attached you are to the current settlement. If you play as the next member in a family that could be hardwaved as a reason for good and bad things from past games becoming more and more muted in subsequent playthoughs. Getting very high ratings like Stahlmark relations -90 could be used be unlock special decorations / structures (example: ports that produce warships with +2 speed, +2 experience). Though that might leave players feeling forced to play to extremes to get the good buildings so that might not be a good idea.
A visual representation of your wealth like a mansion in the Home Counties would be a nice touch certainly. I think I'd prefer to stay as the same character all the way through, rather than go under an alias or be the next member in a family. Its easier to get attached to single character than to a whole family. Special structures dependant on faction relation would be nice, but they shouldn't be essential or anything, just fun little additions so that people don't feel as if they have to go out of their way to get them.
My preference would be for any player's avatar to not be visible in the settlement itself, just to minimize complications and behaviour consistency-breakers. The idea of seeing the Junior Bureaucrat on the title/menu screen (similar to the Borderlands 2 main menu) has appeal though, standing on their Home Counties estate in front of any reward manor, wearing the regalia and surrounded by the other fruits of their labours... Gives another use for the procedural building extruder. On first install or reset, they'd be standing in an unmarked green field, of course.
We should definitely have the option to start an entirely new campaign without abandoning the current one
It could affect who is willing to follow you in a new settlement. EG If you have shown yourself to be particularly set to the rythims of the holy cog then when you embarq you are more likely to start out with followers of the Holy Cog.