I always thought that Void killed them and took their powers, and one day Griffith will kill the current Godhand. But that doesn't seem like something Void would do. Some people think the Skull Knight killed them but I don't think he's strong enough to do that.
Maybe they're still alive and Void is trying to create two Godhands. But even with Griffith there would only be 9/10 members.
I have a theory that the longer you're a Godhand the less human you look, which would explain Maleficentitty and the Vagina thing. Void is only a spine after all, maybe he started out with a complete skeleton? Slan also looks kind of normal.
I wouldn't be surprised if it turns out they are still alive, but they lost their position and will fight Griffith.