most likely. Still, i'm not sure i would call Invalidus a void lord, as it may just be a buffed up voidwalker instead. Blizzard really needs to distinguish the name and meaning between void lord (capital big bads) and voidlords (buff voidwalkers)
Unless... What if the Void lords, are just voidwalkers? But they are myriad, reflecting the voids thing about thousands truths and all possible ways. Each void lord is a true void lord, but also just a voidwalker... until it is time for them to be a big bad. would be to high of a concept perhaps, but a fascinating idea.