Title says it all. I'm hoping for the Void Lords to look like bigger and badder Old Gods, with each Void Lord being similar to their corresponding Old God. (i.e the Void Lord who created C'Thun will look similar to him, and the Void Lord who created Yogg-Saron will have maws, etc (Judging that the Void Lords actually have a corresponding Old God)).
I hope Blizzard don't make the void Lords just plain void silhouettes like the current void walkers.. That would be very disappointing and boring.