This is just a thought but I would love an online department store where everybody could set up their own storefronts and sell items. So for example when you set up your store you get a floor identification (which people use to access your shop...kinda like how the dream town works in animal crossing new leaf)
The reason I said floor identification and not store identification is that some players would get the same floor identification.....so there might be maybe 8 different player run stores on the same floor and they would be like your neighbours
Think of it as a mix between the dream town feature in animal crossing new leaf, the online player run stores in fashion boutique and Join Avenue from pokemon.
I doubt it would ever happen but I would really love something like this included in the game, it would fit in with their desire to make players feel more connected in-game.