I rather strongly suspect that blackrock will have a continued use in this story line. Otherwise, there would be no need for blackrock to continue spawning.

At the very least, it will be desirable as a weapon against the shadowlords. It may also be something you can give the shadowlords. You could, after all, give the ethereal shadowlords blackrock...

There is also a (slim) chance that it will have turn-in value.

~M