It's true that a lot of things have been covered in the span of Rueshima till I guess the Clown arc? A lot of those things tied into one another though, Arima, Eto, OEK, and Aogiri were like a back to back sequence. > V
It's pretty certain that they're the final big bad of the series. One aspect of the story that a lot of people questioned was who the main villain was. It definitely wasn't Arima, nor Eto or Furuta since they've been pushing Kaneki to take down V this entire time, Furuta ehh his agendas are mixed but he wanted Kaneki to become merciless to finish V to an extent. There's still the birdcage surrounding the world, and so on so forth. I highly doubt all of this could be resolved among other important things in 60 chapters though. I guess we'll have to see.