The symmetry won't be maintained, and that's a good thing. In 4e, while it occasionally led to innovation ... like the Avenger, for example, it led to a lot of grid filling, see the never-ending arguments about a Martial Controller or the Ardent (I think that was the Psionic Leader).
I've seen attempts to codify and name a class for every possible 2 domain combos, but I don't think that that should happen, lol.
That said, the Void currently has 4 classes.
Witch - Sage and Dread*
Warlock - Grace and Dread*
Brawler - Bone and Valor
Assassin - Blade and Midnight
The last Darrington Q&A suggested that they are updating the Void this week with the Bloodhunter (Blade and Blood*). There was also a custom Arcana and Splendor class in the Daggerheart Hell's Bells session, but I'm not sure that it'll be also put up.