But like people have guessed it could be primal but i think that will be november or release.
But it could be primal because we have no idea if you could play as the bosses in some form in primal.
What ever it may be it will definetly be big, my votes on the desert or some new gamemode.
Its probably not dragons, but if you look closely each egg has the the same main colors as the bosses.
Green is broodmother, blue is mega, and the black might be the dragon.