Besides that post you tagged, I also made one about
marrying just about any NPC in the game, even townspeople and villager peasants which I also feel falls into this category.
I believe everyone currently wishes for more fleshed out relationships, diplomacy, politics, marriage, dynasty, succession and human interactions.
If this is approached correctly, a game could even be extended indefinitely with infinite game time.
You could unite a kingdom, grow old, start playing as one of your children or a completely different person in the world, the king(previous you) dies, succession battles begin, the kingdom is broken apart, smaller factions and foreigners come and start to take fiefs, everything starts all over again with all the king's sons and daughters fighting together and against foreigners.
If TW approaches this just right, they can create the most epic game ever in a matter of being possible to play it forever and always having something to do to enjoy yourself with a never ending story of several lineages or following a single bloodline forever.
I also believe TW is listening closely to us on this topic and considering quite heavily the impact this can and will have in the game and the depth of the world within the game, so that now is precisely the time for us to make some noise, suggest and comment what we want, what we expect and what we believe to be feasible and within reach while it is still being dilapidated.