I mean, it is basically insanity for them not to support their own cloud save system for tent pole first party franchise. When they designed the save system they knew it would need to work for AC, and when they designed AC they knew how the close save system worked and had the power to change it if they needed to.
So par for the course for them w/ saves.
They will probably release an amibo that can transfer one save game but also melts after the save is removed from it.