Things the next Animal Crossing needs:
Strawberries, watermelons, grapes, peppers, and blueberries that very rarely appear in your town and can be planted to start an orchard
Be able to make fruits into pies to give to your villagers or to display
More pattern storage for your player on-hand
Being able to have a say on where a villager can place their house
Different environments for towns (mountains, savanna, rainforest) to give each town a unique appearance
Add-ons for the Cafe like an ice-cream parlor or bakery
Bat and salamander villagers
Able to buy scuba gear to dive down to see coral reefs and the ocean floor
Villagers having the ability to act like jerks if you treat them badly
A cavern where you can occasionally find ore or bugs
More additions to your home (balcony, watchtower, hidden doors, extended reading nooks, etc)
Backpacks, scarves, earmuffs/headphones, long dresses
Ability to ask a specialized NPC to move rocks in your town
Grass seeds for naturally eroded parts in your town (seriously, my paths are grassy but everywhere else is ugly dirt)
EDIT: not having to tan for proper skin tone (I can’t believe I forgot this one, oops)