Oda wrote the whole thing conciously knowing that the SHP would end up fighting the government. Either the GK come back for the climax of the arc(very possible, and Sommers hasn´t been confirmed dead by Imcel yet, which is obviously relevant) or this is literally it. When has Oda had completely new arc opponents show up during the very climax of an arc, after the FV has already arrived, and we´ve had an arc of building up other characters?
You´re just coping. There´s no new characters that will arrive on Elbaf, and certainly not Shamrock, who was purposefully written out of the arc. At most you could maybe see Loki being DR´d, but even that is increasingly pretty unlikely.