I think this is a very similar topic, and actually provides an interesting sounding mechanic to compromise with the whole “kingdom” thing.
We know that the team want you to focus on your individual settlement, and that they want you to essentially know the inner workings of your settlement. Obviously when you create more than one settlement you start moving into the territory of a different style of game.
Whilst it is something I imagine quite a few people would like, it would seem like it has to be managed appropriately.
I personally feel that if the way you are suggesting was to make it in, those other settlements would have to be completely autonomous. I imagine it would be pretty chaotic trying to manage the systems of each settlement.
They way you’ve described it @ManOfRet reminds me of Sim City, where you would build a city in one region, link it up to the edges, build a city in the adjacent region and the two could interact in terms of commuting, waste, water electricity etc. (If I remember correctly).