While Animal Crossing: New Horizons won’t support data transfer or cloud saves, Nintendo has announced that they’re “considering” implementing a save data backup feature, which would only be available to Nintendo Switch Online users.
As explained on the game’s official site:
“Animal Crossing: New Horizons isn’t supported by Nintendo Switch Online’s Save Data Cloud Backup. However, we’re currently considering a function to backup save data, uniquely for the software, in case one’s Nintendo Switch console itself gets damaged, lost, or stolen.
The use of this feature is limited to Nintendo Switch Online subscribers. The implementation period has yet to be determined, but we’ll make an announcement as soon as a decision is made.”
The site also reiterates that only one island can be created per console, so if you own two Switches you can’t transfer island data from one to the other.
Animal Crossing: New Horizons is currently set to release globally on March 20.
Source: Siliconera