Official Website
http://www.luminous-productions.com/
The studio is called Luminous Productions. It will be headed up by Hajime Tabata, director of Final Fantasy XV. According to Square Enix, it will primarily develop AAA games as well as new and unique entertainment experiences.
Square Enix’s official announcement (via 4gamer) adds that the studio’s original core members will be comprised of FFXV team members. An announcement will be made in mid-2018 regarding the studio’s new project.