The GadgetHelpLine preview claims that you can flip cities with religion and that there's a religious victory.
"In the same vein the Religion system has also been built upon from Civilization V: Gods and Kings Expansion, the methods of going about the rarely seen Religious victory are changed, now religion allows you to breed Inquisitors, apostles, the ability to conquer foreign cities through religious fervour alone is now entirely doable, and in this way Civilization VI has really come alive in all the ways that Civilization V didn’t."
"In the same vein the Religion system has also been built upon from Civilization V: Gods and Kings Expansion, the methods of going about the rarely seen Religious victory are changed, now religion allows you to breed Inquisitors, apostles, the ability to conquer foreign cities through religious fervour alone is now entirely doable, and in this way Civilization VI has really come alive in all the ways that Civilization V didn’t."