"This software does not support "Cloud save backup" feature in Nintendo Switch Online. We are planning to have a save backup function for this software, available to Nintendo Switch Online users. Schedule of this feature is unconfirmed. We will keep you updated. "
So some form of backup is coming.
Man I want the AC direct.
From translations I've heard they're only thinking about it, but not making any promises.
It's like that in all games 1 town with multiple profiles Switch allows up to 8 as opposed to 4 from before.
"Don't fix a bad system because it's always been bad!" However, for handhelds it at least made more sense since they're more personal than shared by the whole family like a console, and at least on the Gamecube you need only buy another memory card. On Switch you'd need to buy another whole system if you want your own Island (you'll probably want your own copy as well), and this method also seems to be preventing cloud saves and user transfers as they're not system based like New Horizon's save is.
The better way is this, each user profile gets it's own Island and can create up to 8 Villagers. This satisfies both those who want to share and those who don't, and it keeps the save user based for compatibility with cloud and transfers. Crazy idea I know, but if even Pokemon did away with the arbitrary 1 save file per cartridge limit, Animal Crossing has absolutely no excuse. We can only hope they were too dumb to see this simple n superior method, rather than purposely forgoing it in order to strong arm people into buying their own Switches.