While official save data backup support through Nintendo Switch Online will not be supported in Animal Crossing: New Horizons, it appears Nintendo is developing an alternative means to backup save data.
Animal Crossing: New Horizons will not support cloud save data backup through Nintendo Switch Online’s existing system; however, Nintendo is working on a “customized method” for backing up save data in case of a lost or broken Switch.
This method will be exclusive to Nintendo Switch Online members, but timing for the release of this feature is currently unknown.
“This game does not support Nintendo Switch Online Cloud Saves, but we are currently looking into a customized method for backing save data up that will be specific to this game in the event that your Nintendo Switch is damaged or lost. This function will be limited to Nintendo Switch Online subscribers. The timing of implementation is undecided and will be announced as soon as it is finalized.”
Additionally, Twitter user Chris Becker found that Japanese and UK listings for Animal Crossing: New Horizons have gone up on the Nintendo eShop.
On the UK listing, there’s a note that Save Data Cloud support is currently “pending.”
— Chris Becker (@SuperNintendad) February 6, 2020
What this means is unknown.
Animal Crossing: New Horizons launches worldwide on March 20th, 2020!