What happens if a Devil Fruit is destroyed?
I don't think you can separate destroyed and being eaten, eating a devil fruit in One Piece pretty much destroys it. So destruction by power, physical force and or being eaten could be considered as being the same. 

That being said, I would think the same thing would happen in any instance of it being 'destroyed', it will 'respawn' and take on the form of it's closest 'relative'.