I guess this means that the four full art GXs within the set will be Reshiram, Kingdra, Dragonite, and Altaria, and the Hyper Rares/Rainbows will be Reshiram, White Kyurem, Salamence, and Altaria (as the Dragonite and Kingdra rainbow arts are included in the premium collection box).
I hope the White Kyurem GX / Salamence GX boxes are similar in style to the Zoroark GX / Raichu GX boxes we got for Shining Legends, though it's odd that they are releasing the two boxes simultaneously rather than staggering them as they did for Shining Legends.