I have a few theories about what's going to happen pretty soon-
It's very possible that noprops will release Ao Oni version 7 that incorporates three new characters. The novel that's coming out features Naoki, Shun and Anna as well. This is actually what happened to corpse party - which now has several mangas, an anime, and professional spin off games. Corpse Party started as an indie rpg (less well-made than Ao Oni actually), and fangames helped it take off. After a few years, more canon installments were released and the game was updated to accomodate new characters and plot changes.
We'll see! Pictures of the new cast below.
Top Panel: Shun and Hiroki
Middle Panel: Anna and Mika
Bottom Panel: Takeshi, Takuro, Naoki