It has been officially announced.
It will air live on the WWE Network
It will be from Jeddah (where Greatest Royal Rumble took place)
Advertised: Goldberg, Roman Reigns, The Undertaker, Kofi Kingston, Braun Strowman, Seth Rollins, AJ Styles, and Brock Lesnar.
Not Advertised: Women
https://www.wwe.com/worldwide/article/wwe-superstars-return-to-jeddah-june-2019