Franky’s words at the bottom of this page seem ominous.
With the initial force invading Elbaf loosing, I wouldn’t be surprised if when Imu arrives, he brings with him the full roster of the HKs. These guys are one of the major factions in the finale so there’s really no point in hiding them.
If the conflict in Mariejois is over, I think we could get Imu, Shamrock, and 4 other HKs arriving in Elbaf. That would give us 8 HKs, which alongside the Gorosei would give us 13 immortals serving Imu, the number the Gorosei told Harald.
If such an invasion happens, you’d certainly have stakes that surpass that of Egghead, especially since Imu himself would be in the fray.

