We know that if a Devil Fruit user dies, their fruit reappears (see In One Piece, does a Devil Fruit reappear after the user dies?). However, this doesn't answer the question of what happens when the fruit gets destroyed without being eaten. I don't know if that's even possible, but I imagine so with sufficient effort.
If a devil fruit is destroyed, would the fruit reincarnate in a nearby fruit (the same as when the user dies), or would it be destroyed for good?
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'.
The only way you can get a canon answer is from the source. Yet, seeing as there is no way to just destroy anything, this situation is completely void, since it would never happen, and would have no reason to.
Since canon won't happen, here's some speculation: Since nothing can be destroyed, whatever remains of the fruit (and there will be remains) will be eaten by bacterium. After the bacteria dies, the fruit will be reborn. So, I guess iKlsR was as right as you could hope for.
This question has been already answered here:
In One Piece, does a Devil Fruit reappear after the user dies?
In summary, when the ability user dies, the ability reborns in another fruit.
