✽ I want the cool new features included in HHD to be sent over to the next main AC game: The freedom to locate houses and buildings, having yards that you can customize, having darker skin tones without tanning, customizing your villagers, schools, villagers drinking and eating, etc. And bring in the new furniture too!
✽ The Campsite and Cafe should stay. Hotels do sound nice too. I want different villagers that visit my town especially when my town gets better. Maybe that will motivate me (and perhaps some other players) to put some effort and have a goal in the game. The better the town gets, the more campers/visitors will come over.
If the next main game is in 3DS or the next handheld with a Streetpass feature, maybe let the voided villager camp in the town first before moving? And maybe campers visit another town by opening your gates online or by Streetpass.
✽ More unique and interesting dialogues. Long, interesting dialogues occur to me once in a blue moon. Make the villagers a bit more unique with the other villagers in their similar personality type by saying something different! I don't want to consider Bones as a dog version of Stitches, or Yuka is just Kitty with a koala body. I want the dialogues to be different with the villagers that moved in, transferred from a different village, and those who previously camped or visited the cafe. I find it inconsistent when a Streetpassed snooty villager said that she was a singer from my town when she was younger despite saying that she never been to the town prior to her move.
✽ If I like the villager and s/he likes me too, then s/he should stay longer and not ping me about leaving every week then leaves in a instant when you didn't played for 2 days. I want my friendships with my villagers to be worthwhile. If I ignored a villager or s/he got mad at me for doing pesky things such as trapping him/her or keep on hitting him/her with a hammer/net, then s/he should be the one to ask to leave the town first than the villagers I've befriended.
✽ Make visits in Dream Towns a bit more worthwhile. Like, acquiring some mementos that were given as a reward for doing a task/befriending a villager in your dream. While we're on the topic of Dream Towns, it would be nice if my old villager will acknowledge my existence too, not just my current villagers.
✽ The shopping card should return.
✽ More side stories and sidequests involving NPCs.
✽ An easier way to place PWPs and have the ability to move and rotate PWPs.
✽ An option to expand the town and the number of villagers that can reside. I also liked the island. Maybe have more places to visit, such as a mountain or a cave with exotic fruits and exclusive creatures. I want the islander feature to return, I never experienced it myself but it sounds like an interesting concept.
✽ A bigger storage for items, letters, and patterns.
✽ Not exactly necessary, but I actually want to attach an extra page to a letter.
✽ Maybe let us have more use with the Amiibo cards? How about sending a villager to your town by scanning their Amiibo card? It would encourage Amiibo card owners to trade their cards, especially with the ones with multiple copies of a single card.
✽ Now for some wishful thinking: I wanted to play as an animal and customize whatever I wanted to look like.