The announcement of these boxes feels really strange to me.
We're on the cusp of moving to Sun & Moon, where we already know EXs will not be printed (at least not in the first set), and the game is moving away from the Mega Evolution mechanic. Why, oh why then are we getting new
Mega Pokemon EX introduced as late as April?!
On the one hand I'm happy because I had previously wanted Sharpedo and Camerupt to get their Megas but, on the other hand, I was looking forward to the new GX Pokemon being given room to develop.
Who knows - maybe the new Megas will be bad and no one will play them? Let's wait and see.
@MarshalBry makes a very good point; will these Promos have XY or SM borders?