Source - PokeBeach:
www.pokebeach.com/2018/05/dragon-majesty-special-set-releasing-in-america-this-fall
"Like 2016’s Generations and 2017’s Shining Legends, the set’s booster packs will only release through promo products, such as pin boxes and premium collections. As you can tell by the set name, the cards will originate from Japan’s Dragon Storm mini-set.
The first two English products will release in America and Europe on September 7th — the “Latios or Latias Dragon Majesty Pin Collections.” They’ll come with a never-before-seen foil promo of Latios or Latias, a pin of the featured Pokemon, three Dragon Majesty booster packs, and a PTCGO code card. Both Pokemon will be Dragon-types.
There is no Latios and Latias in Dragon Storm, so they may originate from SM7 Charisma of the Wrecked Sky, which is Japan’s Hoenn-themed set. They may also be upcoming promos in Japan. We know that our August Celesial Storm set will contain over 160 cards, and since SM7 Charisma of the Wrecked Sky has over 96 cards and SM6b Champion Road has over 66 cards, TPCi won’t need to steal too much from SM7 to create our Dragon Majesty set."