I think it would be best as a separate thing from Animal Crossing but in the same genre. The concept sounds cool and interesting and can really be built upon as it's own game.
As for AC, I could see them doing some space themed villagers. I know Ione already exists, but we don't have a villager who wears a space suit like Knox wears knight armor. (unless that is something Nintendo is moving away from) Also, having a villager or NPC with antenna would be adorable. Maybe they could be based off of a green snail or something like Piccolo from Dragon Ball.