Kamen Rider OOO will appear in the upcoming episodes of Kamen Rider ZI-O and maybe Kamen Rider Faiz too. Recently Kamen Rider 555 Actors Kento Handa (Takumi Inui / Kamen Rider Faiz) & Kohei Murakami (Masato Kusaka / Kamen Rider Kaixa) have posted about some filming. Could that be related to ZI-O?
Silhouettes of Kamen Ride4 ZI-O OOO Armor & is that Geiz Faiz Armor? is seen the magazine scan. So it is believed that those two worlds (time) will be next. If they are gonna appear then they will appear in Episode 7 to 10 arcs.