Unfortunately, that's all we know for now. As of less than two weeks ago, Index Corporation was in trouble, undergoing a bankruptcy-esque proceeding following being under investigation for crooked business practices. Atlus president Naoto Hiraoka told Kotaku at the time, "Currently, Index Digital Media, Inc. and the Atlus brand are unaffected by the Index Corporation proceedings in Japan."
However, the trademark is in Index Corporation's name, so it's unclear if this will have an effect the next hypothetical Persona game, but we've contacted Atlus about this an are awaiting reply.
The last brand new game in the Persona series was 2008's PS2 swan song Shin Megami Tensei: Persona 4. It was later re-released on Vita with additional content as Persona 4: Golden, which Simon Parkin really liked.