Considering the lack of pokemon grey/whatever, I doubt Pokemon Z will ever come to be. Well, that rhymed. (Inb4zed)
I think that was more because of how the story worked; they would had to have made one of the two games canon if they made a single third edition. Thus, I cannot say which is more likely until we see this game's story.
The official Megami Tensei Art Loki of the Shin Megami Tensei IV board. Why? Why not? Because. Maybe. Exactly. My hair is bigger than you.