I doubt very much we're going to see an actual Void-focused expansion,
as technically us dealing with the Void now in the story is basically tying up loose ends of the original storyline that EW is completing, allowing the story to move in a new direction from 7.0 onwards. The Void also cannot be restored fully either, as that would completely invalidate all the many FATEs, repeatable battles and levequests that involve Voidsent crossing over to the Source and the First, so at best you'll probably see just a partial restoration if that (Troia? The nameless ruins Zero had claimed as her diminion?), but otherwise it's the same as it has always been, like the Empty in the First being restored during Eden but still looks like it always is from outside.
As for the Cloud of Darkness, I'm pretty sure in 6.2 it was mentioned that she's no longer around, and that explains why the Voidsent are fighting amongst themselves, in that they're taking aqdvantage of the power vaccum left in her wake (6.2 and beyond revealed Voidsent can actually die for good if another Voidsent 'eats' them by completely consuming their aether - like what happened to the unfortunate Beatrice during the Fell Court of Troia, who was consumed by Scarmiglione.). Canis canim edit is the fundamental aspect of the Void and it's chaotic environment, so this rings true.
Hence the Cloud of Darkness probably won't be reappearing (we did fight a version of her in Eden though, although that was more just a Primal-like recreation and not the real thing).
Either way, the big kicker that we're not going to see the Void in a new expansion is simply because Yoshi himself said there is no hints about how the next expansion is going to go in the current storyline, meaning, no Void sorry. We'll find out either way.