My prediction is Koby will try to convince Smoker to head back to Hachinosu and save Garp. After Egghead, on their way to Elbaf, Nami or Robin will reveal to Luffy that Garp was missing in Hachinosu, so Luffy, Zoro and Sanji will decide to go to Hachinosu while the other half of the crew will go to Elbaf (Robin and Usopp will go).
This way we will have BB's arc, and then Elbaf. (Like WCI and Wano).