Given infinite time and money, I would love to see what they would do if they double down on the sim elements of settlements, fleshing it out in much of the way that Sim Settlements did. Allow players to treat it as a garden, which can survive on it's own but can really grow and thrive given a bit of a guiding hand. What I found most frustrating about settlements in Fallout 4 was that it felt like it came at the cost of hand-crafted cities and settlements.