That specific prophecy was already thwarted in the SCW. Mogo still stands, Ranx lost, the Children of the White Lobe were destroyed and scattered. And Sodam isn't any more dead than Superman was at the end of All-Star.
My thought is that the Black will be one of the energies Sodam will make part of him. My guess in Legion of 3 Worlds was that all the others had been subsumed into the green, possibly all bound by Will. (And really, do any of them actually work without Will, except the Black?)