The next big free update for Animal Crossing: New Horizons will be available this November. Details on the update are vague at best, but a dedicated Animal Crossing Direct presentation will air in October to provide more info.
Animal Crossing Direct
Tune in for a livestreamed #AnimalCrossing: New Horizons Direct in October to learn more about the new content coming to your island in November. Look out for more details to come in the near future. The air date for the stream has not yet been confirmed by Nintendo, but be sure to follow the official Animal Crossing Twitter account to find out.
But from the look of the teaser The Roost and Brewster are at least confirmed.