Yes, he will. He said he would make a place for Xerneas and Yveltal on twitter. "I'll ask my builder to build a new area for me. Every area has a dedicated legendary -- I'm thinking this one would be Yveltal and Xerneas." He didn't say it would be in March, but possiblity. He would also add something for St. Patricks Day.  What do I predict it will look like? Well, it would be with flowers for X, a place to fly (with a flying type pokemon) for Y, but im still not sure with Z. Z is Zygarde , the Order Pokemon. Z could be hidden somewhere. I believe there will be Kalos pokemon mostly in the patches there, because the series "XY & Z." Well, back to the place where you fly. There will be a invisible patch to look for flying pokemon. The flowers, encounters will be Flabebe (Rare), Bellsprout, Oddish, Shaymin (Land Forme and 30% chance), Budew, and Hoppip. Since you have to evolve Floette with a shiny stone, wish_z will maybe add a shiny stone. Well, what about Z you say? Z will have a cave inside with Rock & Ground type pokemon. So X can be found in flowers, Y will be found in the sky, and Z will be found in a cave. Any questions? Leave it down in the comments!