I believe if we were to get a new AC then it would be really cool if when someone new was going to plot, Isabelle would want us to directly go to the town hall where you meet the new villager. From then on, you go with the villager and plot where you would like their house.
It would also be really cool if like HHD, each villager had a front garden which was entered first before entering the villagers house and customized to each villagers style.
There should be more PWP's introduced and it would be even better if PWP's could be used in the front gardens.
Customizing your house should be similar to HHD where you can directly move any furniture you have in your characters posession into the room and move it about with the touch screen!
I really hope some of the Gamecube villagers such as Maddie and Claude who made a return in HHD, return back into the main series games!