New PTCG sets have been announced, with the Alter Genesis one, which will release on September 6, 2019 and will feature 95 cards plus secret rares. Speculating on past generations release pattern, this set will probably be the last Sun & Moon main set, though this hasn’t been confirmed.
The dummy pack art hints at Dialga & Palkia, and Solgaleo & Lunala as the main characters of Alter Genesis, so we most likely will have the two pairs as Tag Team GX cards.
A second set has been announced: High Class Pack 2019, which will release on October 4, 2019. The set will come with booster packs of 11 cards each (instead of the usual 5), including one guaranteed GX and a holo Energy card. The set includes 173 cards (plus secret rares).