My theory is that a BCV or a necromancer will use a version of the dark hollow, to consume most if not all the remaining elders of the BCV. The concentration of the power in the elders could create something very dangerous.
Would that even
work? I'm honestly not sure.
Black Court are the real deal, the actual, true vampires. They're
dead[/b]. I'm not sure a Darkhallow could consume them, since I'm not sure there's anything there to consume. It might be a little like trying to eat hunger. In fact, I wouldn't be shocked to learn that there's a connection or similarity between what a Darkhallow does and what's inside a Black vampire.
I could be wrong, though, IDR any word of JB on the matter.