Villagers don’t move out without your permission in New Horizons, so you don’t have to worry about anyone leaving! The only “consequences” you’ll have to deal with are weeds and flowers growing, your character having “bed head” when you boot the game up, your streak of bonus Nook Miles from the Nook Stop Terminal reverting back to day 1, cockroaches in your house (unless you have the Beautiful Island ordinance in effect), and your villagers commenting on how long it’s been since they’ve last spoken to you and how they’ve missed you. All of these are temporary and fixable, though!