I don't know. I would think that manufacturing DE blades depends on a lot more heavy, expensive machinery than soap manufacruring. It may not be profitable to keep such machinery operating for a niche market only.
I'm not pessimistic though, I think that DE blades will remain popular enough for the foreseeable future.
Good point. The raw materials are also cheaper for soap. The point is, uh... stop poking holes in my example!