What do you guys think will happen in Z, or do you think there will be a Pokemon Z?

Zygarde seems pretty set up to show up during Lysandre's plan, or if Xerneas/Yveltal fight like Groudon and Kyogre in Ruby and Sapphire, because of Zygarde's dex entry saying it shows up whenever the ecosystem is thrown out of balance. He seems to serve a Rayquaza like purpose within it's legendary trio.

Or Game Freak could just do X2/Y2 and make me sad again