User blog comment:Hawkinz340/The underground garbage dump/@comment-178.128.150.251-20131016130134/@comment-13876472-20131016171300

I have made the same thought and I suppose a lot of people too. With Sad substance destroyed and its creator dead Artificial Zoans are ... limited edition items.

One straight explanation is that the factory holds enough stock production, so Doflamingo could have the possibility to negotiate with Kaido. Although, I agree that this is not the most possible scenario. It seems to me too, that this factory keeps also another role in Doflamingo's business with Kaido.

As for Caesar, right now, he is useless. Law managed to drag Doffy out of his palace and he is keeping him busy so as long as Caesar continues to live he is a threat for Law's plan.

My bet is that Law swapped his heart with Caesar's (yes, once again) and now he is fighting Doffy with Caesar's heart on his chest. It would be nice plot evolution to see Doffy pierces Law's chest with his whip and accidentally kills Caesar instead of Law. I imagine a synchronization of this strike with the destrution of the factory by the Straw Hats. Ouch! That will be too harsh for our Fallen Celestial.