He might be wrapping up the story because remember the Levely arc ended, which happened in between the Yonko arcs.
We got the revos in the Levely arc, and Aramaki around the end of Wano.
All we need is the whirlpool man and Imu’s face to unlock all silhouettes.
There’s more DF powers to reveal, but those don’t take up space.
Levely arc is all about Vivi, that could lead up to her joining the crew at the end, or have something to do with Pluton(latter more likely).